mlxsw: spectrum: Fix EEPROM access in case of SFP/SFP+

The current code does not handle correctly the access to the upper page
in case of SFP/SFP+ EEPROM. In that case the offset should be local
and the I2C address should be changed.

Fixes: 2ea10903

 ("mlxsw: spectrum: Add support for access cable info via ethtool")
Reported-by: Florian Klink <flokli@flokli.de>
Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>