ivy: Add a possiblity for mainboard early init.

This is needed for stout EC init.

Change-Id: I5c73499c17763229840152a473a2d820802ee2f6
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: https://review.coreboot.org/13535
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/mainboard/gigabyte/ga-b75m-d3h/romstage.c b/src/mainboard/gigabyte/ga-b75m-d3h/romstage.c
index 8278820..ff85ce1 100644
--- a/src/mainboard/gigabyte/ga-b75m-d3h/romstage.c
+++ b/src/mainboard/gigabyte/ga-b75m-d3h/romstage.c
@@ -205,3 +205,6 @@
 	DMIBAR32(0x0e2c) = 0x20000000;
 }
 #endif
+
+void mainboard_early_init(int s3resume) {
+}