PIC32MZ serial drivers, tested with Microchip MEB II board With FreeRTOS 7.6.0

This is an update of the PIC32 serial driver that work with new PIC32MZ processor.

Its based on the serial driver provided in the standard demo format.

Tested on a Multimedia Extension Board II (MEB II) DS320005-2 with a DM320006 started kit, PIC32MZ2048ECH144