mb/google/fizz: Enable Wake-on-Lan feature

This patch enables WOL feature.

BUG=b:69290148
BRANCH=None
TEST=powerd_dbus_suspend && sudo etherwake -i eth0 $MAC to make sure
     the system could be woken up by WOL packet.

Change-Id: I1178a776db2cdb448fe6650d49ae6c0281ac1128
Signed-off-by: Gaggery Tsai <gaggery.tsai@intel.com>
Reviewed-on: https://review.coreboot.org/22606
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/fizz/devicetree.cb

@@ -291,6 +291,7 @@ chip soc/intel/skylake
 		device pci 1c.0 on # PCI Express Port 1
 			chip drivers/net
 				register "customized_leds" = "0x0fa7"
+				register "wake" = "GPE0_PCI_EXP"
 				device pci 00.0 on end
 			end
 		end # PCI Express Port 1