Use fast memset in SMM mode, too

... and always include IP checksumming in romstage.
It's generally useful and our upcoming port needs it.

Change-Id: I248402d96a23e58354744e053b9d5cca6b74ad3a
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/827
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/x86/lib/Makefile.inc

@@ -15,6 +15,7 @@ romstage-y += cbfs_and_run.c
 romstage-y += memset.c
 romstage-y += memcpy.c
 
+smm-y += memset.c
 smm-y += memcpy.c
 
 $(obj)/arch/x86/lib/console.ramstage.o :: $(obj)/build.h