Do not set a bit in the PxSACT register

Setting a bit in the PxSACT register for a command in the command list
indicates to the controller that the command list slot contains a
native queued command (NCQ).  This can cause problems with some
controllers (one such controller is the Marvell 9128).  Since NCQ
commands are not used, don't set the PxACT register for commands issued.

Signed-off-by: Chris Ruffin <chris.ruffin@...>