bnx2x: Fix passive DAC cable detection

Fix Passive DAC detection for specific cables, such that even in case
SFP_CABLE_TECHNOLOGY option is not set in the EEPROM (offset 8), treat it as a
passive DAC cable, since some cables don't have this indication.

Signed-off-by: Yaniv Rosner <yanivr@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>