UPSTREAM: arm64: mm: Move ASID from TTBR0 to TTBR1

In preparation for mapping kernelspace and userspace with different
ASIDs, move the ASID to TTBR1 and update switch_mm to context-switch
TTBR0 via an invalid mapping (the zero page).

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 commit 7655abb953860485940d4de74fb45a8192149bb6)

[toddpoynor@google.com: add missing mrs inst from context]
Change-Id: I9575ae2f0b3b5383c44f7ace0ac50588be739e45
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Git-commit: a72dd8a6
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>