arch/x86: Avoid HAVE_SMI_HANDLER conditional with smm-class

Build of the entire smm-class is skipped if we have
HAVE_SMI_HANDLER=n.

Change-Id: I10b4300ddd18b1673c404b45fd9642488ab3186c
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34125
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Lance Zhao <lance.zhao@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/Makefile.inc

@@ -404,8 +404,6 @@ smm-y += memmove.c
 smm-y += memset.c
 smm-$(CONFIG_X86_TOP4G_BOOTMEDIA_MAP) += mmap_boot.c
 
-ifeq ($(CONFIG_HAVE_SMI_HANDLER),y)
 ifneq ($(wildcard src/mainboard/$(MAINBOARDDIR)/smihandler.c),)
 smm-srcs += src/mainboard/$(MAINBOARDDIR)/smihandler.c
 endif
-endif