UPSTREAM: binderfs: rename header to binderfs.h

It doesn't make sense to call the header binder_ctl.h when its sole
existence is tied to binderfs. So give it a sensible name. Users will far
more easily remember binderfs.h than binder_ctl.h.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 136497735
(cherry picked from commit c13295ad219d8bb0e47942d4cfc8251de449a67e)
Change-Id: Ide6275bbbaec2e25df19e11754afb7f1827888b2
Signed-off-by: Hridya Valsaraju <hridya@google.com>