src: Remove unused '#include <cpu/x86/smm.h>'

Change-Id: I1632d03a7a73de3e3d3a83bf447480b0513873e7
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41685
Reviewed-by: David Guckian
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/spi/spi_flash.c

@@ -4,7 +4,6 @@
 #include <boot_device.h>
 #include <boot/coreboot_tables.h>
 #include <console/console.h>
-#include <cpu/x86/smm.h>
 #include <string.h>
 #include <spi-generic.h>
 #include <spi_flash.h>