arm64: lib: Import latest version of Arm Optimized Routines' strncmp

arm64: lib: Import latest version of Arm Optimized Routines' strncmp

Import the latest version of the Arm Optimized Routines strncmp function based
on the upstream code of string/aarch64/strncmp.S at commit 189dfefe37d5 from:
  https://github.com/ARM-software/optimized-routines

This latest version includes MTE support.

Note that for simplicity Arm have chosen to contribute this code to Linux under
GPLv2 rather than the original MIT OR Apache-2.0 WITH LLVM-exception license.
Arm is the sole copyright holder for this code.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220301101435.19327-3-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>