SAMV7:  Add a sneak internal interface that will allow us to set the MAC address before NSH even starts

SAMV7: Updates to Ethernet driver based on comparison with Atmel sample code.  Add configuration for other PHY GPIOs.  Still no Ethernet interrupts

PIC32MZ: Changes that will permit building of the PIC32MZ Start Kit configuration using MPLAB and the XC32 toolchain.  From David Sidrane

Extend the AT24 EEPROM driver so that it supports: (1) the byte-oriented read() method, (2) parts with extended memory regions, and (3) parts with 8-bit addressing.

SAMV7: Quick'n'dirty port of the SAMA5D4 Ethernet MAC driver to the SAMV7.  Still some unresovled issues with DCache handling

This commit enables HSMCI functionality in the SAMV71-XULT.  TX DMA is, unfortunately, currently disabled.