mb/emulation/qemu-q35: Support PARALLEL_MP with SMM_ASEG

Tested with SMI_DEBUG: SMM prints things on the console.

Change-Id: I7db55aaabd16a6ef585c4802218790bf04650b13
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61494
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/cpu/intel/smm_reloc.h

@@ -36,6 +36,7 @@ struct ied_header {
 /* These helpers are for performing SMM relocation. */
 void northbridge_write_smram(u8 smram);
 
+void smm_open_aseg(void);
 void smm_lock(void);
 void smm_relocate(void);