hikey: Optimize CPU Targets for each variant

hikey has A53 cores, while hikey960 has A73 and A53 cores.  Bionic
now has A73-specific configuration, so this CL uses the optimal
CPU configuration for both targets.

Change-Id: I5f15c8fdc43fcab5e4f01b3685f3e19b9916c0bf
3 files changed