x86/xen: fix memory setup for PVH dom0

Since af06d66ee32b (x86: fix setup of PVH Dom0 memory map) in Xen, PVH
dom0 need only use the memory memory provided by Xen which has already
setup all the correct holes.

xen_memory_setup() then ends up being trivial for a PVH guest so
introduce a new function (xen_auto_xlated_memory_setup()).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>

arch/x86/xen/xen-ops.h

@@ -36,6 +36,7 @@ void xen_mm_unpin_all(void);
 void xen_set_pat(u64);
 
 char * __init xen_memory_setup(void);
+char * xen_auto_xlated_memory_setup(void);
 void __init xen_arch_setup(void);
 void xen_enable_sysenter(void);
 void xen_enable_syscall(void);