ethtool, net/mlx4_en: Cable info, get_module_info/eeprom ethtool support

Added support for get_module_info/get_module_eeprom ethtool support for cable info reading.

Added new cable types enum in include/uapi/linux/ethtool.h for ethtool use.
+#define ETH_MODULE_SFF_8636            0x3
+#define ETH_MODULE_SFF_8636_LEN        256
+#define ETH_MODULE_SFF_8436            0x4
+#define ETH_MODULE_SFF_8436_LEN        256

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>