scsi: csiostor: Replace PCI pool old API

The PCI pool API is deprecated. This commit replaces the PCI pool old
API by the appropriate function with the DMA pool API. It also updates
the name of some variables and the content of comments, accordingly.

Signed-off-by: Romain Perier <romain.perier@collabora.com>
Reviewed-by: Peter Senna Tschudin <peter.senna@collabora.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>