hv: correctly grant DRHD register access rights to hypervisor

Need to call hv_access_memory_region_update() explicitly for DRHD
registers to correctly grant access rights for hypervisor.

Currently, other hv_access_memory_region_update() calls happen to
cover the DRHD addresses for currently supported platforms.

Tracked-On: #3194
Signed-off-by: Zide Chen <zide.chen@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

Author: ZideChen0

hypervisor/arch/x86/vtd.c

@@ -213,6 +213,9 @@ static int32_t register_hrhd_units(void)
 		drhd_rt->index = i;
 		drhd_rt->drhd = &platform_dmar_info->drhd_units[i];
 		drhd_rt->dmar_irq = IRQ_INVALID;
+
+		hv_access_memory_region_update(drhd_rt->drhd->reg_base_addr, PAGE_SIZE);
+
 		ret = dmar_register_hrhd(drhd_rt);
 		if (ret != 0) {
 			break;