[media] c8sectpfe: fix ininitialized error return on firmware load failure

static analysis with cppcheck detected the following error:

[drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c:1210]:
  (error) Uninitialized variable: ret

ret is never initialised, so garbage is being returned. Instead
return the error return from the call of request_firmware_nowait

Signed-off-by: Colin Ian King <colin.king@canonical.com>