intel/stm: Drop now unneeded num_cpus param

Suggested by Nico Huber in CB:38766

Change-Id: Ib8a340f17a12951bc6bc67e3093046575e7b0e46
Signed-off-by: Eugene D Myers <cedarhouse@comcast.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40438
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/cpu/x86/mp_init.c

@@ -741,7 +741,7 @@ static void asmlinkage smm_do_relocation(void *arg)
 		mseg = mp_state.perm_smbase +
 			(mp_state.perm_smsize - CONFIG_MSEG_SIZE);
 
-		stm_setup(mseg, p->cpu, runtime->num_cpus,
+		stm_setup(mseg, p->cpu,
 				perm_smbase,
 				mp_state.perm_smbase,
 				runtime->start32_offset);