msm: camera: fix untrusted pointer for power down setting

When getting power down setting, there is an untrusted pointer
from a user space pointer.Need to copy to the kernel space first.

Change-Id: I0c66e942453581caac5ea00a54a252840a32972f
CRs-Fixed: 2037398 2037403
Signed-off-by: Terence Ho <terenceh@codeaurora.org>