Update libata driver for bf548 atapi controller against the 2.6.24 tree.

Changes:
1. Remove irq_ack() and port_disable() methods
2. Acocomodate for the libata-link patches
3. Change Kconfig ATAPI mode option into a module param.
4. Add supported WMDMA mode.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>