msm: camera: null check validation of a pointer at right place

Camera is not functional due to wrong null pointer check.
Added the check validation at correct place.

Change-Id: Ic37afa8396a5a3670516237a5212ad5e2f2a7fb1
Signed-off-by: Viswanadha Raju Thotakura <viswanad@codeaurora.org>
Signed-off-by: Vivek Veenam <vveenam@codeaurora.org>