x86 SMM: Replace weak prototypes with weak function stub

Change-Id: I682617cd2f4310d3e2e2ab6ffec51def28a4779c
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/7961
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/southbridge/amd/agesa/hudson/smihandler.c b/src/southbridge/amd/agesa/hudson/smihandler.c
index d1b661b..af8c215 100644
--- a/src/southbridge/amd/agesa/hudson/smihandler.c
+++ b/src/southbridge/amd/agesa/hudson/smihandler.c
@@ -41,8 +41,7 @@
 		break;
 	}
 
-	if (mainboard_smi_apmc)
-		mainboard_smi_apmc(cmd);
+	mainboard_smi_apmc(cmd);
 }
 
 int southbridge_io_trap_handler(int smif)
@@ -66,8 +65,7 @@
 	/* Only Bits [23:0] indicate GEVENT SMIs. */
 	if (status & gevent_mask) {
 		/* A GEVENT SMI occurred */
-		if (mainboard_smi_gpi)
-			mainboard_smi_gpi(status & gevent_mask);
+		mainboard_smi_gpi(status & gevent_mask);
 	}
 
 	/* Clear events to prevent re-entering SMI if event isn't handled */