NET: Improvied I/O buffer logic
Left out some changes in last commit
SAMA5:  Rename most EMAC definitions to EMAC0 to handle the SAMA5D4 which has to EMAC modules and no GMAC
SAMA5:  Add pin mux definitions for the SAMA5D4
Minor naming fix
SAMA5D4: Let's consistently use the name XDMAC for the SAMA5D4 DMA module
SAMA5D4:  Has two XDMA modules
SAMA5D4:  Add beginning of XDMAC register definition header file (incomplete)
Updated ChangeLog
Finishes the SAMA5D4 XDMAC register definition header file
SAMA5: Cosmetic clean-up of README files