tg3: prevent scheduling while atomic splat

The problem was introduced in commit
506b0a39 ("[netdrv] tg3: APE heartbeat changes"). The bug occurs
because tp->lock spinlock is held which is obtained in tg3_start
by way of tg3_full_lock(), line 11571. The documentation for usleep_range()
specifically states it cannot be used inside a spinlock.

Fixes: 506b0a39 ("[netdrv] tg3: APE heartbeat changes")
Signed-off-by: NJonathan Toppins <jtoppins@redhat.com>
Acked-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -820,7 +820,7 @@ static int tg3_ape_event_lock(struct tg3 *tp, u32 timeout_us)
 
 		tg3_ape_unlock(tp, TG3_APE_LOCK_MEM);
 
-		usleep_range(10, 20);
+		udelay(10);
 		timeout_us -= (timeout_us > 10) ? 10 : timeout_us;
 	}