xen: make xen_flush_tlb_all() static

xen: make xen_flush_tlb_all() static

xen_flush_tlb_all() is used in arch/x86/xen/mmu.c only. Make it static.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
OraBug: 26662731

(cherry picked from commit c71e6d804c88168ecf02aaf14e1fd5773d683b5f)
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Conflicts:
	arch/x86/xen/mmu.c
	(Different location of xen_flush_tlb_all())