mlxsw: core: Fix wrong SFP EEPROM reading for upper pages 1-3

Fix wrong reading of upper pages for SFP EEPROM. According to "Memory
Organization" figure in SFF-8472 spec: When reading upper pages 1, 2 and
3 the offset should be set relative to zero and I2C high address 0x51
[1010001X (A2h)] is to be used.

Fixes: a45bfb5a

 ("mlxsw: core: Extend QSFP EEPROM size for ethtool")
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>