refactor(mte): deprecate CTX_INCLUDE_MTE_REGS

Currently CTX_INCLUDE_MTE_REGS is used for dual purpose,
to enable allocation tags register and to context save and restore
them and also to check if mte feature is available.

To make it more meaningful, remove CTX_INCLUDE_MTE_REGS
and introduce FEAT_MTE. This would enable allocation tags register
when FEAT_MTE is enabled and also supported from platform.

Also arch features can be conditionally enabled disabled based on
arch version from `make_helpers/arch_features.mk`

Change-Id: Ibdd2d43874634ad7ddff93c7edad6044ae1631ed
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/docs/design/firmware-design.rst b/docs/design/firmware-design.rst
index 3fce393..24efabe 100644
--- a/docs/design/firmware-design.rst
+++ b/docs/design/firmware-design.rst
@@ -2771,7 +2771,7 @@
    (at EL0 and S-EL0) if it is only supported at EL0. If instead it is
    implemented at all ELs, it is unconditionally enabled for only the normal
    world. To enable it for the secure world as well, the build option
-   ``CTX_INCLUDE_MTE_REGS`` is required. If the hardware does not implement
+   ``ENABLE_FEAT_MTE`` is required. If the hardware does not implement
    MTE support at all, it is always disabled, no matter what build options
    are used.
 
@@ -2860,7 +2860,7 @@
 
 --------------
 
-*Copyright (c) 2013-2023, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.*
 
 .. _SMCCC: https://developer.arm.com/docs/den0028/latest
 .. _PSCI: https://developer.arm.com/documentation/den0022/latest/