atp870u: Replace port 0x80 delay by udelay

tscam() is using port 0x80 access for delays but that's x86-only.
Use udelay(2) instead.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Reviewed-by: Hannes Reinicke <hare@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>