truncate: drop 'oldsize' truncate_pagecache() parameter

truncate_pagecache() doesn't care about old size since commit
cedabed49b39 ("vfs: Fix vmtruncate() regression").  Let's drop it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3d9b503..928df79 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -985,7 +985,7 @@
 	unmap_mapping_range(mapping, holebegin, holelen, 0);
 }
 
-extern void truncate_pagecache(struct inode *inode, loff_t old, loff_t new);
+extern void truncate_pagecache(struct inode *inode, loff_t new);
 extern void truncate_setsize(struct inode *inode, loff_t newsize);
 void truncate_pagecache_range(struct inode *inode, loff_t offset, loff_t end);
 int truncate_inode_page(struct address_space *mapping, struct page *page);