UPSTREAM: binderfs: drop lock in binderfs_binder_ctl_create

The binderfs_binder_ctl_create() call is a no-op on subsequent calls and
the first call is done before we unlock the suberblock. Hence, there is no
need to take inode_lock() in there. Let's remove it.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <christian@brauner.io>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 136497735
(cherry picked from commit 29ef1c8e16aed079ac09989d752e38d412b6e1a8)
Change-Id: I7c294796ac7891f62387e09dc34332ca4c3ee67b
Signed-off-by: Hridya Valsaraju <hridya@google.com>