UPSTREAM: arm64: mm: Introduce TTBR_ASID_MASK for getting at the ASID in the TTBR

UPSTREAM: arm64: mm: Introduce TTBR_ASID_MASK for getting at the ASID in the TTBR

There are now a handful of open-coded masks to extract the ASID from a
TTBR value, so introduce a TTBR_ASID_MASK and use that instead.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
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 b519538dfefc2f8478a1bcb458459c861d431784)

[toddpoynor@google.com: fixup context, asm-uaccess.h changes to
uaccess.h]
Change-Id: Ia456c58c83f9bbd02177cefb8e3106dfffe357cc
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>