A fix for errata 835769 may be available in revisions r0p2, r0p3 or r0p4
of the Cortex-A53 processor. The presence of the fix is determined by
checking bit 7 in the REVIDR register.

If the fix is present we report ERRATA_NOT_APPLIES which silences the
erroneous 'missing workaround' warning.

Change-Id: Ib75b008e755e9ac648554ca9398024fdbea4a91a
Signed-off-by: Jonathan Wright <jonathan.wright@arm.com>