ANDROID: fs/proc: Perform priority inheritance around access_remote_vm()

It holds mmap_sem lock which is a hot path. Some debug daemons can end
up holding this lock to get the cmdline of a process, which can result
in slowing down this process.

Add hooks around the calls to allow vendors to implement a simple prio
inheritance scheme to deal with this.

Bug: 289412815
Signed-off-by: Qais Yousef <qyousef@google.com>
Change-Id: I160637b30e5bd58d5978b25be8a21ce025175ec3