linux-phytec-fsl

uio: add missing error codes

My static checker complains that "ret" could be uninitialized at the
end, which is true but it's more likely that it would be set to zero.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>