bnx2x: fix I2C non-respondent issue

When I2C is not responding it's usually due to a previous
unexpected reset during I2C operation. We release it by
powering down and up the SFP+ module.

Signed-off-by: Yaniv Rosner <yaniv.rosner@broadcom.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>