arm64: Enable TIMER_IMX_SYS_CTR for ARCH_MXC platforms

ARCH_MXC platforms needs system counter as broadcast timer
to support cpuidle, enable it by default.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
1 job for cpuidle_testing in 14 minutes and 52 seconds (queued for 2 seconds)