spi: lpspi: Avoid potential use-after-free in probe()

fsl_lpspi_probe() is allocating/disposing memory manually with
spi_alloc_host()/spi_alloc_target(), but uses
devm_spi_register_controller(). In case of error after the latter call the
memory will be explicitly freed in the probe function by
spi_controller_put() call, but used afterwards by "devm" management outside
probe() (spi_unregister_controller() <- devm_spi_unregister() below).

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070
...
Call trace:
 kernfs_find_ns
 kernfs_find_and_get_ns
 sysfs_remove_group
 sysfs_remove_groups
 device_remove_attrs
 device_del
 spi_unregister_controller
 devm_spi_unregister
 release_nodes
 devres_release_all
 really_probe
 driver_probe_device
 __device_attach_driver
 bus_for_each_drv
 __device_attach
 device_initial_probe
 bus_probe_device
 deferred_probe_work_func
 process_one_work
 worker_thread
 kthread
 ret_from_fork

Fixes: 5314987d

 ("spi: imx: add lpspi bus driver")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://msgid.link/r/20240312112050.2503643-1-alexander.sverdlin@siemens.com
Signed-off-by: Mark Brown <broonie@kernel.org>