bnx2x: Remove unneccessary EXPORT_SYMBOL

bnx2x_schedule_sp_rtnl is exported by bnx2x, although no other module
uses it.

Reported-by: Benjamin Poirier <bpoirier@suse.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>