Staging: vc04_services: Fix a couple error codes

These are accidentally returning positive EINVAL instead of negative
-EINVAL.  Some of the callers treat positive values as success.

Fixes: 7b3ad5ab

 ("staging: Import the BCM2835 MMAL-based V4L2 camera driver.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>