drm/i915/gvt: fix getting 64bit bar size error

For 64bit bar while reading the higher 32bit the value should be returned
directly.

In the current implementation the higher 32bit value was discarded and not
written to the cfg space of vgpu which lead to an incorrect bar size.
Signed-off-by: NXiaoguang Chen <xiaoguang.chen@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/gvt.h

@@ -361,6 +361,8 @@ static inline void intel_vgpu_write_pci_bar(struct intel_vgpu *vgpu,
 		 * leave the bit 3 - bit 0 unchanged.
 		 */
 		*pval = (val & GENMASK(31, 4)) | (*pval & GENMASK(3, 0));
+	} else {
+		*pval = val;
 	}
 }