media: ov5640 mipi v2: fix kernel warning when no camera is plugged in

the regulator need to be disabled before calling regulator_put().
If not do so, the kernel will print warning message as below.

[    2.834247] ov5640_mipi 1-003c: Camera is not found
    [    2.839198] ------------[ cut here ]------------
    [    2.844386] WARNING: CPU: 0 PID: 33 at drivers/regulator/core.c:2039 _regulator_put+0x34/0xd8
    [    2.852954] Modules linked in:
    [    2.856091] CPU: 0 PID: 33 Comm: kworker/0:1 Not tainted 5.3.0-rc3-next-20190809-5.3-warrior-next+g1dc2946 #1
    [    2.866044] Hardware name: NXP i.MX8MQ EVK (DT)
    [    2.870692] Workqueue: events deferred_probe_work_func
    [    2.875879] pstate: 60000005 (nZCv daif -PAN -UAO)
    [    2.880712] pc : _regulator_put+0x34/0xd8
    [    2.884756] lr : _regulator_put+0x34/0xd8
    [    2.888802] sp : ffff00001210b5f0
    [    2.892153] x29: ffff00001210b5f0 x28: ffff0000111ca238
    [    2.897478] x27: ffff000011db1850 x26: ffff000011db1790
    [    2.902800] x25: ffff000011db1790 x24: 0000000000000009
    [    2.908151] x23: ffff00001210b698 x22: ffff8000baec9e00
    [    2.913501] x21: ffff000011c498c8 x20: ffff8000baecc100
    [    2.918852] x19: ffff8000baecc100 x18: 0000000000000010
    [    2.924202] x17: 0000000000000000 x16: 0000000000000000
    [    2.929553] x15: ffffffffffffffff x14: ffff000011c498c8
    [    2.934904] x13: ffff00009210b387 x12: ffff00001210b38f
    [    2.940254] x11: ffff000011c62000 x10: ffff00001210b310
    [    2.945605] x9 : 00000000ffffffd0 x8 : ffff0000106e31a0
    [    2.950955] x7 : 0000000000000124 x6 : ffff000011e63b43
    [    2.956305] x5 : 0000000000000000 x4 : 0000000000000000
    [    2.961655] x3 : 00000000ffffffff x2 : e14ea0006ddd6c00
    [    2.967006] x1 : 0000000000000000 x0 : 0000000000000024
    [    2.972390] Call trace:
    [    2.974884]  _regulator_put+0x34/0xd8
    [    2.978588]  regulator_put+0x2c/0x40
    [    2.982227]  devm_regulator_release+0x10/0x18
    [    2.986640]  release_nodes+0x1b0/0x220
    [    2.990429]  devres_release_all+0x34/0x58
    [    2.994480]  really_probe+0x1b8/0x2e8
    [    2.998184]  driver_probe_device+0x74/0x118
    [    3.002406]  __device_attach_driver+0x80/0xb8
    [    3.006805]  bus_for_each_drv+0x78/0xc8
    [    3.010653]  __device_attach+0xd4/0x130
    [    3.014528]  device_initial_probe+0x10/0x18
    [    3.018746]  bus_probe_device+0x90/0x98
    [    3.022624]  device_add+0x48c/0x720
    [    3.026150]  device_register+0x1c/0x28
    [    3.029975]  i2c_new_client_device+0x130/0x2a0
    [    3.034431]  i2c_new_device+0xc/0x20
    [    3.038061]  of_i2c_register_device+0x70/0x98
    [    3.042457]  of_i2c_register_devices+0x98/0x120
    [    3.047026]  i2c_register_adapter+0x160/0x410
    [    3.051395]  __i2c_add_numbered_adapter+0x58/0x90
    [    3.056137]  i2c_add_adapter+0x9c/0xc8
    [    3.059925]  i2c_add_numbered_adapter+0x24/0x30
    [    3.064507]  i2c_imx_probe+0x3d0/0x880
    [    3.068296]  platform_drv_probe+0x50/0xa0
    [    3.072318]  really_probe+0xdc/0x2e8
    [    3.075933]  driver_probe_device+0x74/0x118
    [    3.080127]  __device_attach_driver+0x80/0xb8
    [    3.084522]  bus_for_each_drv+0x78/0xc8
    [    3.088397]  __device_attach+0xd4/0x130
    [    3.092268]  device_initial_probe+0x10/0x18
    [    3.096461]  bus_probe_device+0x90/0x98
    [    3.100332]  deferred_probe_work_func+0x64/0x98
    [    3.104956]  process_one_work+0x1e0/0x320
    [    3.109007]  worker_thread+0x228/0x428
    [    3.112812]  kthread+0x120/0x128
    [    3.116104]  ret_from_fork+0x10/0x18
    [    3.119722] ---[ end trace 69a95d03ced5eb6c ]---

Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>