msm: camera_v2: cci: check for NULL pointer

in function "msm_cci_subdev_g_chip_ident"
check for NULL pointer and return error
instead of assert

Change-Id: Ia27751c4d6f3d5ead1749e396ffa5c2773f1582b
Signed-off-by: Georgi Hristov <ghristov@codeaurora.org>