backlight: crbllcd_bl - Use platform_device_register_simple()

Use platform_device_register_simple() and also fix error
handling when platform_device_alloc() fails (cr_backlight_driver
is left registered).

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>