Dynamically configure timers' base frequency for Armada 38x
Instead of using 'clock-frequency' device tree property for global/twd
mpcore timers of Armada 38x SoCs, set it in platform_late_init stage
with arm_tmr_change_frequency() function.
Reviewed by: cognet (mentor)
Approved by: cognet (mentor)
Obtained from: Semihalf
Differential Revision: https://reviews.freebsd.org/D11881