net: sxgbe: add basic framework for Samsung 10Gb ethernet driver

This patch adds support for Samsung 10Gb ethernet driver(sxgbe).

- sxgbe core initialization
- Tx and Rx support
- MDIO support
- ISRs for Tx and Rx
- ifconfig support to driver

Signed-off-by: Siva Reddy Kallam <siva.kallam@samsung.com>
Signed-off-by: Vipul Pandya <vipul.pandya@samsung.com>
Signed-off-by: Girish K S <ks.giri@samsung.com>
Neatening-by: Joe Perches <joe@perches.com>
Signed-off-by: Byungho An <bh74.an@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>