octeontx2-pf: Add basic ethtool support

This patch adds ethtool support for
 - Driver stats, Tx/Rx perqueue and CGX LMAC stats
 - Set/show Rx/Tx queue count
 - Set/show Rx/Tx ring sizes
 - Set/show IRQ coalescing parameters

Signed-off-by: Christina Jacob <cjacob@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>