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>

drivers/staging/media/atomisp/i2c/ov5693/atomisp-ov5693.c

@@ -1714,6 +1714,8 @@ static int ov5693_detect(struct i2c_client *client)
 	}
 	ret = ov5693_read_reg(client, OV5693_8BIT,
 			      OV5693_SC_CMMN_CHIP_ID_L, &low);
+	if (ret)
+		return ret;
 	id = ((((u16)high) << 8) | (u16)low);
 
 	if (id != OV5693_ID) {