Revert "s390x: reduce TARGET_PHYS_ADDR_SPACE_BITS to 62"

This reverts commit 311f83ca.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

target-s390x/cpu.h

@@ -34,10 +34,7 @@
 #include "exec/cpu-defs.h"
 #define TARGET_PAGE_BITS 12
 
-/* Actually 64-bits, limited by the memory API to 62 bits.  We
- * never use that much.
- */
-#define TARGET_PHYS_ADDR_SPACE_BITS 62
+#define TARGET_PHYS_ADDR_SPACE_BITS 64
 #define TARGET_VIRT_ADDR_SPACE_BITS 64
 
 #include "exec/cpu-all.h"