drivers/video/backlight/max8925_bl.c: drop devm_kfree of devm_kzalloc'd data

devm_kfree() allocates memory that is released when a driver detaches.
Thus, there is no reason to explicitly call devm_kfree in probe or remove
functions.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>