feat(brbe): test that EL3 has properly enabled access to BRBE

Access to FEAT_BRBE control registers must be explicitly enabled in EL3,
this simple test just ensures that the registers are accessible or traps
to EL3, similar to the TRBE test.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I0a25c5ce6beb6aa96b9428264b75cb3569ac535a
7 files changed