ethtool: Add fallback to get_module_eeprom from netlink command

In case netlink get_module_eeprom_by_page() callback is not implemented
by the driver, try to call old get_module_info() and get_module_eeprom()
pair. Recalculate parameters to get_module_eeprom() offset and len using
page number and their sizes. Return error if this can't be done.

Signed-off-by: Vladyslav Tarasiuk <vladyslavt@nvidia.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>