[media] radio-bcm2048: don't ignore errors

Remove this warning:

drivers/staging/media/bcm2048/radio-bcm2048.c: In function 'bcm2048_set_rds_no_lock':
drivers/staging/media/bcm2048/radio-bcm2048.c:467:6: warning: variable 'err' set but not used [-Wunused-but-set-variable]
  int err;
      ^~~

By returning the error code.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/staging/media/bcm2048/radio-bcm2048.c

@@ -482,6 +482,8 @@ static int bcm2048_set_rds_no_lock(struct bcm2048_device *bdev, u8 rds_on)
 					   flags);
 		memset(&bdev->rds_info, 0, sizeof(bdev->rds_info));
 	}
+	if (err)
+		return err;
 
 	err = bcm2048_send_command(bdev, BCM2048_I2C_FM_RDS_SYSTEM,
 				   bdev->cache_fm_rds_system);