[PATCH] sata_nv ADMA/NCQ support for nForce4

This patch adds support for ADMA mode on NVIDIA nForce4 (CK804/MCP04) SATA
controllers to the sata_nv driver.  Benefits of ADMA mode include:

- NCQ support

- Reduced CPU overhead (controller DMAs command information from memory
  instead of them being pushed in by the CPU)

- Full 64-bit DMA support

ADMA mode is enabled by default in this version.  To disable it, set the
module parameter adma_enabled=0.

Signed-off-by: Robert Hancock <hancockr@shaw.ca>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>