feat(hcx): add TF, TFTF, and group entries for FEAT_HCX

This patch adds support for automated test of TF-A support for
enabling FEAT_HCX. This feature can't be tested through normal means
since some models support it and others don't, and the TFTF test has
no way of knowing whether or not its been enabled in the TF-A build
in use.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I374e191db3b61c43362b54c8d2c2c38e806e8aaf
3 files changed