octeontx2-pf: MTU, MAC and RX mode config support

This patch addes support to change interface MTU, MAC address
retrieval and config, RX mode ie unicast, multicast and promiscuous.
Also added link loopback support

Signed-off-by: Tomasz Duszynski <tduszynski@marvell.com>
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>