[TF-A] Deprecating CTX_INCLUDE_MTE_REGS build option.

Hi All,

Please note build option CTX_INCLUDE_MTE_REGS is now replaced with ENABLE_FEAT_MTE[1] To avoid breaking any builds for timebeing CTX_INCLUDE_MTE_REGS usage will indirectly enable ENABLE_FEAT_MTE but will produce a build warning.

Kindly request anyone using CTX_INCLUDE_MTE_REGS to replace with ENABLE_FEAT_MTE As option CTX_INCLUDE_MTE_REGS backward support will be removed after next release and going forward usage of CTX_INCLUDE_MTE_REGS will not be handled within build.

-- Thanks, Govindraj R

[1]: https://review.trustedfirmware.org/q/topic:%22gr/refac_mte%22