Fix compile of ciss(4) with CISS_DEBUG defined

Obtained from:	Yahoo! Inc.
MFC after:	2 weeks
Except one case mps(4) driver does not touch the data and works well with
unmapped I/O.  That one exception is access to INQUIRY VPD request result.
Those requests are never unmapped now, but to be safe add respective check
there and allow unmapped I/O for the SIM by setting PIM_UNMAPPED flag.