Add cortex_a53_64 and cortex_a53_a57

Renames cortex_a53 to cortex_a53_64, since we need to set options for
both. Also adds the cortex_a53_a57 big/little configuration.

Change-Id: Ia0e8104867f9aed7cbf5be8be1ead6ddc30c42c4
1 file changed