Remove unused and deprecated mc_capable() and smt_capable().

Both were added recently by f6e763b9 ("arm64: topology:
Implement basic CPU topology support"). Uses of both were removed
by 8e7fbcbc ("sched: Remove stale power aware scheduling
remnants and dysfunctional knobs").
Signed-off-by: NZi Shen Lim <zlim@broadcom.com>
Signed-off-by: NMark Brown <broonie@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>