Revert "pagemap: do not leak physical addresses to non-privileged userspace"

This reverts commit 1ffc3cd9a36b504c20ce98fe5eeb5463f389e1ac.

Don't need it on pandora - even if rowhammer worked, pandora is almost
never a multiuser system, and cache invalidate is a privileged instruction
already on ARM.

pagemap may also be useful for use c64_tools and such.

diff --cc fs/proc/task_mmu.c
Simple merge