[PATCH] eCryptfs: fix possible NULL ptr deref in ecryptfs_d_release()

ecryptfs_d_release() first dereferences a pointer (via
ecryptfs_dentry_to_lower()) and then afterwards checks to see if the
pointer it just dereferenced is NULL (via ecryptfs_dentry_to_private()).

This patch moves all of the work done on the dereferenced pointer inside a
block governed by the condition that the pointer is non-NULL.

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