cpu/amd: Remove empty smm_lock()

Change-Id: I599d1d7e28f3a6439b04ef9bd38f671e1a876e92
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34148
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/cpu/amd/smm/smm_init.c

@@ -70,11 +70,6 @@ void smm_init(void)
 	/* CPU MSR are set in CPU init */
 }
 
-void smm_lock(void)
-{
-	/* We lock SMM in CPU init */
-}
-
 void smm_init_completion(void)
 {
 }