arc: [plat-nsimosci*] use ezchip network driver

Since ezchip network driver was adapted to little endian architecture
this patch provides the corresponding arch/arc/{boot/dts,configs}/ updates so
we can switch over to this device-model/driver for OSCI platform.

Cc: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Lada Trimasova <ltrimas@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>