Remove include <linux/android_pmem.h>

Summary:
This file is not needed and does not exist in the uapi kernel headers.

Change-Id: I7994bfeda07e094f2674a77400390240f361e8d1

Test Plan: verified, part of a big changeset coming up

Reviewers: randall.rushing, jriordan001

Differential Revision: http://review.codefirex.com/D240