driver/misc/fsa9480.c fix potential null-pointer dereference

Signed-off-by: Jonghwan Choi <jhbird.choi@samsung.com>
Cc: Donggeun Kim <dg77.kim@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>