Staging: xgifb: Remove XGIFAIL() macro and its calls.

XGIFAIL() prints a message and returns a value, but it's used only in one
place. Better remove it and replace the call with the macro content.

Signed-off-by: Miguel Gómez <magomez@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>