dts: arm: microchip: Fixes in preparation for boards

We fixed some minor bugs and one missing component for
Microchip MEC5 HAL based chips, MEC174x and MEC175x.
These changes are in preparation for board check-in and
hello world sample. Added the clock-frequency property
to the cpu and rtimer nodes. This properity is used
derive the Kconfig's for the kernel tick.

Signed-off-by: Scott Worley <scott.worley@microchip.com>