nfp: nsp: implement read SFF module EEPROM

The NSP now provides the ability to read from the SFF module EEPROM.
Note that even if an error occurs, the NSP may still provide some of the
data.

Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>