staging: xgifb: eliminate #ifdef XGIFB_PAN

XGIFB_PAN is always defined and checks can be eliminated.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>