FROMLIST: arm64: mm: Allocate ASIDs in pairs

In preparation for separate kernel/user ASIDs, allocate them in pairs
for each mm_struct. The bottom bit distinguishes the two: if it is set,
then the ASID will map only userspace.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git


 commit 0c8ea531b7740754cf374ca8b7510655f569c5e3)
[ghackmann@google.com: adjust context]
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Change-Id: Ie9dd8ca183007c486ef13fd3c560223d263bef4b
Git-Commit: b7032349
Git-repo: git://android.googlesource.com/kernel/common.git


Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>