Another small improvement in SCSI emulation

The message

Error: Inquiry (STANDARD) buffer size 5 is less than 36 (TODO: only 5 required)

was quite annoying, so I attacked it. I used to have a hack which explicitly implemented
inquiry with the allocation size length == 5.
But it turned out that the clean fix is quite trivial, the specification says "if the allocation length of the command descriptor block (CDB) is too small to transfer all of the parameters, the additional length shall not be adjusted to reflect the truncation", so the clean fix for this problem is not longer than the code telling about "TODO". :) Will send the patch upstream. Now probe-scsi in OBP looks really nice:

ok probe-scsi
Target 0
Unit 0 Disk QEMU QEMU HARDDISK 0.11
Target 1
Unit 0 Disk QEMU QEMU HARDDISK 0.11
Target 2
Unit 0 Removable Read Only device QEMU QEMU CD-ROM 0.11
ok