dts: arm: microchip: add dtsi files for Microchip PIC32CZ CA SoC series

Adds common and SoC-specific .dtsi files for the Microchip
PIC32CZ CA80 CA90 and CA91 family. These files define core
peripherals, address maps, and interrupt controller structure
shared across the PIC32CZ CA80 9x variants.

Signed-off-by: Mohamed Azhar <mohamed.azhar@microchip.com>