data-kernel:emac: Support for reading MAC addr from config ini

Read the MAC address from the config file if exists and
assign to ethernet network interface. If file doesnt exist
use the hardcode mac address.

Change-Id: I81c84ab49b9dd4921f1334f3966d9780fd5c3419
Acked-by: Nisha Menon <nmenon@qti.qualcomm.com>
Signed-off-by: Sunil Paidimarri <hisunil@codeaurora.org>