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/mmap.c b/mm/mmap.c
index 2b2b45e..9365a8f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2224,7 +2224,6 @@
 	struct mmu_gather tlb;
 	struct vm_area_struct *vma;
 	unsigned long nr_accounted = 0;
-	unsigned long end;
 
 	/* mm's last user has gone, and its about to be pulled down */
 	mmu_notifier_release(mm);
@@ -2249,7 +2248,7 @@
 	tlb_gather_mmu(&tlb, mm, 1);
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
 	/* Use -1 here to ensure all VMAs in the mm are unmapped */
-	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
+	unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
 	vm_unacct_memory(nr_accounted);
 
 	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);