mlxsw: core: Add support for module EEPROM read by page

Add support for ethtool_ops::get_module_eeprom_by_page() which allows
user space to read transceiver module EEPROM based on passed parameters.

The I2C address is not validated in order to avoid module-specific code.
In case of wrong address, error will be returned from device's firmware.

Tested by comparing output with legacy method (ioctl) output.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>