fs/ecryptfs/: possible cleanups

- make the following needlessly global code static:
  - crypto.c:ecryptfs_lower_offset_for_extent()
  - crypto.c:key_tfm_list
  - crypto.c:key_tfm_list_mutex
  - inode.c:ecryptfs_getxattr()
  - main.c:ecryptfs_init_persistent_file()

- remove the no longer used mmap.c:ecryptfs_lower_page_cache

- #if 0 the unused read_write.c:ecryptfs_read()

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ecryptfs/mmap.c

@@ -34,8 +34,6 @@
 #include <linux/scatterlist.h>
 #include "ecryptfs_kernel.h"
 
-struct kmem_cache *ecryptfs_lower_page_cache;
-
 /**
  * ecryptfs_get_locked_page
  *