VM: make unmap_vmas() return void

same story - nobody uses it and it's been pointless since
"mm: Remove i_mmap_lock lockbreak" went in.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/memory.c b/mm/memory.c
index cfb57b0..016c675 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1316,8 +1316,6 @@
  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
  * @details: details of nonlinear truncation or shared cache invalidation
  *
- * Returns the end address of the unmapping (restart addr if interrupted).
- *
  * Unmap all pages in the vma list.
  *
  * Only addresses between `start' and `end' will be unmapped.
@@ -1329,7 +1327,7 @@
  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
  * drops the lock and schedules.
  */
-unsigned long unmap_vmas(struct mmu_gather *tlb,
+void unmap_vmas(struct mmu_gather *tlb,
 		struct vm_area_struct *vma, unsigned long start_addr,
 		unsigned long end_addr, unsigned long *nr_accounted,
 		struct zap_details *details)
@@ -1372,11 +1370,9 @@
 			} else
 				unmap_page_range(tlb, vma, start, end, details);
 		}
-		start = end;
 	}
 
 	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
-	return start;	/* which is now the end (or restart) address */
 }
 
 /**