gpu: nvgpu: add wrapper for MS_LTC disallow/allow

- add separate wrapper function for sending ALLOW
  and DISALLOW RPCs for MS_LTC engine
- add separate SW blocker function for MS_LTC

Bug 200763448

Change-Id: I80b6c59f6acaec03ab9fcd2e1ce82817f55124b2
Signed-off-by: Divya <dsinghatwari@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2603122
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: svc-mobile-cert <svc-mobile-cert@nvidia.com>
Reviewed-by: Vijayakumar Subbu <vsubbu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

drivers/gpu/nvgpu/os/linux/driver_common.c

@@ -223,6 +223,7 @@ static void nvgpu_init_pm_vars(struct gk20a *g)
 		if (g->elpg_enabled) {
 			nvgpu_set_enabled(g, NVGPU_ELPG_MS_ENABLED,
 						platform->enable_elpg_ms);
+			g->elpg_ms_enabled = platform->enable_elpg_ms;
 		}
 	}