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/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 5b03967..b859924 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -185,12 +185,6 @@
    registers to be included when saving and restoring the CPU context.
    Default is '0'.
 
--  ``CTX_INCLUDE_MTE_REGS``: Numeric value to include Memory Tagging Extension
-   registers in cpu context. This must be enabled, if the platform wants to use
-   this feature in the Secure world and MTE is enabled at ELX. This flag can
-   take values 0 to 2, to align with the ``FEATURE_DETECTION`` mechanism.
-   Default value is 0.
-
 -  ``CTX_INCLUDE_NEVE_REGS``: Numeric value, when set will cause the Armv8.4-NV
    registers to be saved/restored when entering/exiting an EL2 execution
    context. This flag can take values 0 to 2, to align with the
@@ -313,6 +307,11 @@
    flag can take the values 0 to 2, to align  with the ``FEATURE_DETECTION``
    mechanism. Default value is ``0``.
 
+-  ``ENABLE_FEAT_MTE``: Numeric value to enable Memory Tagging Extension
+   if the platform wants to use this feature in the Secure world and MTE is
+   enabled at ELX. This flag can take values 0 to 2, to align with the
+   ``FEATURE_DETECTION`` mechanism. Default value is ``0``.
+
 -  ``ENABLE_FEAT_MTE_PERM``: Numeric value to enable support for
    ``FEAT_MTE_PERM``, which introduces Allocation tag access permission to
    memory region attributes. ``FEAT_MTE_PERM`` is a optional architectural
@@ -1334,7 +1333,7 @@
 
 --------------
 
-*Copyright (c) 2019-2023, Arm Limited. All rights reserved.*
+*Copyright (c) 2019-2024, Arm Limited. All rights reserved.*
 
 .. _DEN0115: https://developer.arm.com/docs/den0115/latest
 .. _PSA FW update specification: https://developer.arm.com/documentation/den0118/a/