[media] s5k5baf: Add missing error check for devm_kzalloc

This patch add a missing a check on the return value of devm_kzalloc,
which would cause a NULL pointer dereference in a OOM situation.

Signed-off-by: Kiran Padwal <kiran.padwal@smartplayin.com>
Acked-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>