KVM: s390: fix fallthrough annotation

A case statement in kvm_s390_shadow_tables uses fallthrough annotations
which are not recognized by gcc because they are hidden within a block.
Move these annotations out of the block to fix (W=1) warnings like below:

arch/s390/kvm/gaccess.c: In function 'kvm_s390_shadow_tables':
arch/s390/kvm/gaccess.c:1029:26: warning: this statement may fall through [-Wimplicit-fallthrough=]
  case ASCE_TYPE_REGION1: {
                          ^
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/gaccess.c

@@ -1050,8 +1050,7 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr,
 		rc = gmap_shadow_r2t(sg, saddr, rfte.val, *fake);
 		if (rc)
 			return rc;
-		/* fallthrough */
-	}
+	} /* fallthrough */
 	case ASCE_TYPE_REGION2: {
 		union region2_table_entry rste;
 
@@ -1077,8 +1076,7 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr,
 		rc = gmap_shadow_r3t(sg, saddr, rste.val, *fake);
 		if (rc)
 			return rc;
-		/* fallthrough */
-	}
+	} /* fallthrough */
 	case ASCE_TYPE_REGION3: {
 		union region3_table_entry rtte;
 
@@ -1113,8 +1111,7 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr,
 		rc = gmap_shadow_sgt(sg, saddr, rtte.val, *fake);
 		if (rc)
 			return rc;
-		/* fallthrough */
-	}
+	} /* fallthrough */
 	case ASCE_TYPE_SEGMENT: {
 		union segment_table_entry ste;