liquidio: added support for ethtool --set-channels feature

adding support for ethtool --set-channels feature

Signed-off-by: Intiyaz Basha <intiyaz.basha@cavium.com>
Signed-off-by: Raghu Vatsavayi <raghu.vatsavayi@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>