media: staging: atomisp: fix the uninitialized use in gc2235_detect()

media: staging: atomisp: fix the uninitialized use in gc2235_detect()

Inside function gc2235_detect(), variable "low" could be uninitialized
if ov5693_read_reg() returns error, however, it affects the value of
variable "id". The "id" is used in the later if statement, which is
potentially unsafe.

Link: https://lore.kernel.org/linux-media/20210711202334.27959-1-yzhai003@ucr.edu
Signed-off-by: Yizhuo <yzhai003@ucr.edu>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>