ASoC: imx-ssi: Use clk_prepare_enable/clk_disable_unprepare

Fix the following kernel crash:

------------[ cut here ]------------
WARNING: at drivers/clk/clk.c:508 __clk_enable+0x9c/0xa8()
Modules linked in:
Backtrace:
[<80011ef4>] (dump_backtrace+0x0/0x10c) from [<803fd48c>] (dump_stack+0x18/0x1c)
 r7:00000009 r6:000001fc r5:803002ac r4:00000000
[<803fd474>] (dump_stack+0x0/0x1c) from [<8002003c>] (warn_slowpath_common+0x54/0x6c)
[<8001ffe8>] (warn_slowpath_common+0x0/0x6c) from [<80020078>] (warn_slowpath_null+0x24/0x2c)
 r9:00000090 r8:8600e2c0 r7:8605c808 r6:8605c800 r5:8605d780
r4:8600e2c0
[<80020054>] (warn_slowpath_null+0x0/0x2c) from [<803002ac>] (__clk_enable+0x9c/0xa8)
[<80300210>] (__clk_enable+0x0/0xa8) from [<803002d0>] (clk_enable+0x18/0x30)
 r5:8605d780 r4:80000013
[<803002b8>] (clk_enable+0x0/0x30) from [<803247c4>] (imx_ssi_probe+0xa0/0x4f4)
 r5:8605d780 r4:86174180
[<80324724>] (imx_ssi_probe+0x0/0x4f4) from [<8022b0fc>] (platform_drv_probe+0x20/0x24)
[<8022b0dc>] (platform_drv_probe+0x0/0x24) from [<80229c40>] (driver_probe_device+0x80/0x1f0)
[<80229bc0>] (driver_probe_device+0x0/0x1f0) from [<80229e44>] (__driver_attach+0x94/0x98)
 r9:00000090 r8:805b7800 r7:00000000 r6:8605c83c r5:805b1b44
r4:8605c808
[<80229db0>] (__driver_attach+0x0/0x98) from [<8022856c>] (bus_for_each_dev+0x68/0x94)
 r7:00000000 r6:80229db0 r5:86033eb0 r4:805b1b44
[<80228504>] (bus_for_each_dev+0x0/0x94) from [<80229aa0>] (driver_attach+0x20/0x28)
 r7:00000000 r6:86174100 r5:8059f6d0 r4:805b1b44
[<80229a80>] (driver_attach+0x0/0x28) from [<80228d50>] (bus_add_driver+0x18c/0x268)
[<80228bc4>] (bus_add_driver+0x0/0x268) from [<8022a474>] (driver_register+0x80/0x134)
[<8022a3f4>] (driver_register+0x0/0x134) from [<8022b4a4>] (platform_driver_register+0x4c/0x60)
 r7:00000000 r6:805b7800 r5:00000018 r4:86032000
[<8022b458>] (platform_driver_register+0x0/0x60) from [<80556890>] (imx_ssi_driver_init+0x14/0x1c)
[<8055687c>] (imx_ssi_driver_init+0x0/0x1c) from [<8000868c>] (do_one_initcall+0x40/0x194)
[<8000864c>] (do_one_initcall+0x0/0x194) from [<8052f3b0>] (kernel_init+0x114/0x1f0)
[<8052f29c>] (kernel_init+0x0/0x1f0) from [<8002445c>] (do_exit+0x0/0x788)
---[ end trace d4aa739205917dbb ]---
asoc: mc13783-hifi <-> imx-ssi.0 mapping ok

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>