(atapi_action, case XPT_SCSI_IO): Enable DMA only for READ and WRITE commands  as some combinations of chipset, controller and target do not behave  correctly when DMA is enabled for other commands.
(atapi_action, case XPT_SCSI_IO): Enable DMA only for READ and WRITE commands
 as some combinations of chipset, controller and target do not behave
 correctly when DMA is enabled for other commands.

PR:		kern/103602
MFC after:	2 weeks

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase