drivers: timer: microchip: xec: Microchip MEC one kernel timer driver

We want to simplify the maintenance burden and confusion of having
more than one driver for the same kernel timer peripheral used on
all Microchip MEC parts. The XEC version of the driver was converted
register definitions in the driver. Register access is performed using
Zephyr sys_read/write architecture specific inline routines. Driver DT
YAML was updated to use phandle for the 32-bit basic timer used for
ARCH_HAS_CUSTOM_BUSY_WAIT support, basic timer max value property,
and GIRQ interrtup aggregator hardware information.
SoC part Kconfigs, chip level/board level DTSI updated to use the
unified driver.

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