sata_sil24: always set protocol override for non-ATAPI data commands

The sil24 hardware has a built-in list of commands and associated protocols
that gets used by default to decide how to handle a given command. However,
if the command is not known to the controller then it presumably assumes it to
be a non-data command which then causes protocol mismatch errors if the device
ends up requesting data transfer. The new DATA SET MANAGEMENT - Trim command
causes this issue since it's a DMA data-out command.

Since we should always know best what protocol the command should be using,
let's just set the override flag to inform the controller what protocol to use
for all non-ATAPI commands with data transfer.

Signed-off-by: Robert Hancock <hancockrwd@gmail.com>
Tested-by: Mark Lord <liml@rtr.ca>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>