cpu/x86/smm: Convert C++ style comment

Originally, this patch made 'BIOS' uppercase in the referenced comment
and converted the C++ style to be consistent with the remainder of
the function.  Somewhere, the 'BIOS' became uppercase creating a merge
conflict.

Now this CL converts the C++ style to be consistent with the remainder
of the comments.

Signed-off-by: Eugene D. Myers <edmyers@tycho.nsa.gov>
Change-Id: I85d78b5e08a7643c3d87e3daf353d6b3ba8d306b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38854
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/cpu/x86/smm/smm_module_loader.c

@@ -396,7 +396,7 @@ int smm_load_module(void *smram, size_t size, struct smm_loader_params *params)
 	/* Does the required amount of memory exceed the SMRAM region size? */
 	total_size = total_stack_size + handler_size;
 	total_size += fxsave_size + SMM_DEFAULT_SIZE;
-	// account for the BIOS resource list
+	/* Account for the BIOS resource list */
 	if (CONFIG(STM))
 		total_size += CONFIG_BIOS_RESOURCE_LIST_SIZE;