refactor(cpus): convert the Cortex-A75 to use cpu helpers

Testing done in conjunction with change 258152.

Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Change-Id: I9082c7a5c68e39d6e419c2a00501d63895ca73c7
(cherry picked from commit 6fafbd56d0000d9f9254563ac92bdbab7d1becad)
1 file changed