xen: Introduce xen_pfn_t for pfn and mfn types

All the original Xen headers have xen_pfn_t as mfn and pfn type, however
when they have been imported in Linux, xen_pfn_t has been replaced with
unsigned long. That might work for x86 and ia64 but it does not for arm.
Bring back xen_pfn_t and let each architecture define xen_pfn_t as they
see fit.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
index 3871e47..42834a3 100644
--- a/include/xen/interface/xen.h
+++ b/include/xen/interface/xen.h
@@ -188,7 +188,7 @@
 	unsigned int cmd;
 	union {
 		/* [UN]PIN_TABLE, NEW_BASEPTR, NEW_USER_BASEPTR */
-		unsigned long mfn;
+		xen_pfn_t mfn;
 		/* INVLPG_LOCAL, INVLPG_ALL, SET_LDT */
 		unsigned long linear_addr;
 	} arg1;
@@ -428,11 +428,11 @@
 	unsigned long nr_pages;     /* Total pages allocated to this domain.  */
 	unsigned long shared_info;  /* MACHINE address of shared info struct. */
 	uint32_t flags;             /* SIF_xxx flags.                         */
-	unsigned long store_mfn;    /* MACHINE page number of shared page.    */
+	xen_pfn_t store_mfn;        /* MACHINE page number of shared page.    */
 	uint32_t store_evtchn;      /* Event channel for store communication. */
 	union {
 		struct {
-			unsigned long mfn;  /* MACHINE page number of console page.   */
+			xen_pfn_t mfn;      /* MACHINE page number of console page.   */
 			uint32_t  evtchn;   /* Event channel for console page.        */
 		} domU;
 		struct {