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

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>
(cherry picked from commit b8b0f559c7b1dcf5503817e518c81c9a18ee45e0)

Conflicts:

	arch/x86/xen/apic.c