ecryptfs: remove unnecessary mux from ecryptfs_init_ecryptfs_miscdev()

The misc_mtx should provide all the protection required to keep the daemon
hash table sane during miscdev registration.  Since this mutex is causing
gratuitous lockdep warnings, this patch removes it.

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