enic: Add new firmware devcmds

Add new firmware devcmds:  CMD_PROXY_BY_INDEX, CMD_CONFIG_INFO_GET

Signed-off-by: Scott Feldman <scofeldm@cisco.com>
Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: Vasanthy Kolluri <vkolluri@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>