uboot-imx

net: mvpp2.c: Clear all buffer / descriptor areas before usage

This fixes problems noticed with the PPv2.2 A7k/8k port, when not all
elements of the descriptors had been cleared before use.

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>