qlge: Fix lock/mutex warnings.

Get rid of spinlock and private mutex usage for exclusive access to the
HW semaphore register.  rtnl_lock already creates exclusive access to
this register in all driver API.
Add rtnl to firmware worker threads that also use the HW semaphore register.

Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>