staging: xgifb: inline XGIfb_query_VGA_config_space()

XGIfb_query_VGA_config_space() is used only once during the init and
can be replaced with a single PCI configuration space read.

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>