arm/xen: remove duplicate arch_gnttab_init() function

This was introduced in commit e306e3be1c (Merge tag
'stable/for-linus-3.17-rc0-tag').

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

arch/arm/xen/grant-table.c

@@ -49,8 +49,3 @@ int arch_gnttab_init(unsigned long nr_shared)
 {
 	return 0;
 }
-
-int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
-{
-	return 0;
-}