ipro100: Check interrupt status in HAIKU_CHECK_DISABLE_INTERRUPTS.

This should make ipro100 behave better on shared IRQ lines.

Should fix #17349.

drivers/network: Move ethernet drivers to an "ether" subdirectory.

Now that there is also a "tap" driver in here, and the WiFi drivers
are also in a subdirectory, moving the physical ethernet device drivers
to a subdirectory also makes sense.

(Briefly) discussed on the mailing lists.