xen/apic/xenbus/swiotlb/pcifront/grant/tmem: Make functions or variables static.

There is no need for those functions/variables to be visible. Make them
static and also fix the compile warnings of this sort:

drivers/xen/<some file>.c: warning: symbol '<blah>' was not declared. Should it be static?

Some of them just require including the header file that
declares the functions.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 1d0d95e..eea81cf 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -286,10 +286,9 @@
 }
 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 
-void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid,
-				    unsigned long frame, int flags,
-				    unsigned page_off,
-				    unsigned length)
+static void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid,
+					   unsigned long frame, int flags,
+					   unsigned page_off, unsigned length)
 {
 	gnttab_shared.v2[ref].sub_page.frame = frame;
 	gnttab_shared.v2[ref].sub_page.page_off = page_off;
@@ -346,9 +345,9 @@
 }
 EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);
 
-void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
-				  int flags, domid_t trans_domid,
-				  grant_ref_t trans_gref)
+static void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
+					 int flags, domid_t trans_domid,
+					 grant_ref_t trans_gref)
 {
 	gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
 	gnttab_shared.v2[ref].transitive.gref = trans_gref;