aha1542: Don't reduce functionality with DEBUG enabled

Enabling DEBUG disables write commands and devices with ID > 1.
Remove this "feature" to allow real debugging.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>