ACPI: Drop typedef global_nvs_t

Bring all GNVS related initialisation function to global
scope to force identical signatures. Followup work is
likely to remove some as duplicates.

Change-Id: Id4299c41d79c228f3d35bc7cb9bf427ce1e82ba1
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42489
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/cpu/x86/smm.h

@@ -86,6 +86,7 @@ struct smm_module_params {
 typedef asmlinkage void (*smm_handler_t)(void *);
 
 /* SMM Runtime helpers. */
+struct global_nvs *smm_get_gnvs(void);
 
 /* Entry point for SMM modules. */
 asmlinkage void smm_handler_start(void *params);