elog: add ELOG_WAKE_SOURCE_GPIO

Provide a GPIO-based wake source event for log caputre.

BUG=b:159947207

Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Change-Id: Iaa15178a392f40156d8d10e9aedfd5a1e758eedb
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44532
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/elog.h

@@ -119,6 +119,7 @@
 #define  ELOG_WAKE_SOURCE_PME_PCIE22       0x29
 #define  ELOG_WAKE_SOURCE_PME_PCIE23       0x2a
 #define  ELOG_WAKE_SOURCE_PME_PCIE24       0x2b
+#define  ELOG_WAKE_SOURCE_GPIO             0x2c
 
 struct elog_event_data_wake {
 	u8 source;