The natsemi driver didn't properly synchronize netif_close/netif_suspend
against a last interrupt or packet.

Result: hang during ifdown with concurrent flood ping.

Additional changes:
* do not enable superflous interrupts (e.g. the drivers relies on TxDone
- TxIntr not needed)
* wait that the hardware has really stopped in close and suspend.
* workaround for the (at least) gcc-2.95.1 compiler problem. Also
simplifies the code a bit.
* disable_irq() in tx_timeout - needed to protect against rx interrupts.
* stop the nic before switching into silent rx mode for wol (required
according to docu).

Patch against 2.4.10. WOL is not tested, but ifup, ifdown, suspend and
resume during flood ping now work.

--
	Manfred