ide-cd: merge cdrom_pc_intr() and cdrom_newpc_intr()

Add handling of REQ_TYPE_{SENSE,ATA_PC} requests to cdrom_newpc_intr()
(please note that these requests never have 'bio' attached to them
and they never use DMA), then remove no longer needed cdrom_pc_intr().

There should be no functionality changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>