staging: xgifb: eliminate XGIfb_fix

Eliminate XGIfb_fix and initialize needed fields of fb_info->fix
in probe().

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