s390/mm: use _SEGMENT_ENTRY_EMPTY in the code

_SEGMENT_ENTRY_INVALID denotes the invalid bit in a segment table
entry whereas _SEGMENT_ENTRY_EMPTY means that the value of the whole
entry is only the invalid bit, as the entry is completely empty.

Therefore we use _SEGMENT_ENTRY_INVALID only to check and set the
invalid bit with bitwise operations. _SEGMENT_ENTRY_EMPTY is only used
to check for (un)equality.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 59ac937..a07b1ec 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -359,8 +359,8 @@ static int __gmap_unlink_by_vmaddr(struct gmap *gmap, unsigned long vmaddr)
 	spin_lock(&gmap->guest_table_lock);
 	entry = radix_tree_delete(&gmap->host_to_guest, vmaddr >> PMD_SHIFT);
 	if (entry) {
-		flush = (*entry != _SEGMENT_ENTRY_INVALID);
-		*entry = _SEGMENT_ENTRY_INVALID;
+		flush = (*entry != _SEGMENT_ENTRY_EMPTY);
+		*entry = _SEGMENT_ENTRY_EMPTY;
 	}
 	spin_unlock(&gmap->guest_table_lock);
 	return flush;
@@ -589,7 +589,7 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
 		return rc;
 	ptl = pmd_lock(mm, pmd);
 	spin_lock(&gmap->guest_table_lock);
-	if (*table == _SEGMENT_ENTRY_INVALID) {
+	if (*table == _SEGMENT_ENTRY_EMPTY) {
 		rc = radix_tree_insert(&gmap->host_to_guest,
 				       vmaddr >> PMD_SHIFT, table);
 		if (!rc)