qlge: Fix deadlock when cancelling worker.

Removing usage of rtnl_lock() to protect firmware interface registers.
These registers are accessed in some worker threads and can create a
deadlock if rtnl_lock is taken by upper layers while the worker is still
pending.
We remove rtnl_lock and use a driver mutex just while mailboxes are
accessed.

Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/qlge/qlge.h b/drivers/net/qlge/qlge.h
index 2282139..9787dff 100644
--- a/drivers/net/qlge/qlge.h
+++ b/drivers/net/qlge/qlge.h
@@ -2083,6 +2083,7 @@
 	u32 mailbox_in;
 	u32 mailbox_out;
 	struct mbox_params idc_mbc;
+	struct mutex	mpi_mutex;
 
 	int tx_ring_size;
 	int rx_ring_size;