UPSTREAM: binderfs: remove wrong kern_mount() call

The binderfs filesystem never needs to be mounted by the kernel itself.
This is conceptually wrong and should never have been done in the first
place.

Fixes: 3ad20fe393b ("binder: implement binderfs")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 136497735
(cherry picked from commit fdd94acd50d607cf6a971455307e711fd8ee16e)
Change-Id: Ife722830ecb64ab75ccdd012043864ae1b10d792
Signed-off-by: Hridya Valsaraju <hridya@google.com>