octeontx2-pf: RVU representor driver

Adds basic driver for the RVU representor.

Driver on probe does pci specific initialization and
does hw resources configuration. Introduces RVU_ESWITCH
kernel config to enable/disable the driver. Representor
and NIC shares the code but representors netdev support
subset of NIC functionality. Hence "otx2_rep_dev" API
helps to skip the features initialization that are not
supported by the representors.

Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>