bnx2x: Restore global registers back to default.

Several KR registers were not set correctly back to default after
loopback test, so set those global registers over the global WC lane (zero)
rather than the current lane.

Signed-off-by: Yaniv Rosner <yanivr@broadcom.com>
Signed-off-by: Barak Witkowski <barak@broadcom.com>
Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>