libata-sff: use ATAPI_{COD|IO}

atapi_pio_bytes() uses bare numbers for the ATAPI interrupt reason bits despite
these are #define'd in <linux/ata.h>.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>