xen: memory : Add new XENMAPSPACE type XENMAPSPACE_dev_mmio

Add a new type of Xen map space for Dom0 to map device's MMIO region.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Tested-by: Julien Grall <julien.grall@arm.com>

include/xen/interface/memory.h

@@ -160,6 +160,7 @@ DEFINE_GUEST_HANDLE_STRUCT(xen_machphys_mapping_t);
 #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another dom,
 				    * XENMEM_add_to_physmap_range only.
 				    */
+#define XENMAPSPACE_dev_mmio     5 /* device mmio region */
 
 /*
  * Sets the GPFN at which a particular page appears in the specified guest's