Drop empty mainboard_ops

Change-Id: I24866142eebcb8fdbc7e21f5b2f364a8d1b264b3
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/1932
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/intel/xe7501devkit/mainboard.c

@@ -1,5 +1,2 @@
 #include <device/device.h>
 
-struct chip_operations mainboard_ops = {
-};
-