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/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index d6cc62c..a4d901d 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -236,7 +236,7 @@
 	return errno_to_pcibios_err(do_pci_op(pdev, &op));
 }
 
-struct pci_ops pcifront_bus_ops = {
+static struct pci_ops pcifront_bus_ops = {
 	.read = pcifront_bus_read,
 	.write = pcifront_bus_write,
 };