media: imx274: fix missing return assignment from call to imx274_mode_regs

The variable ret is being checked for failure however it is not being set
from the return status from the call to imx274_mode_regs. Currently ret is
alwayus zero and the check is redundant. Fix this by assigning it.

Detected by CoverityScan, CID#1460278 ("Logically dead code")

Fixes: 0985dd30 ("media: imx274: V4l2 driver for Sony imx274 CMOS sensor")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>