Fix a problem with the cd(4) driver -- the CAMGETPASSTHRU ioctl wouldn't succeed if there was no media in the drive.
Fix a problem with the cd(4) driver -- the CAMGETPASSTHRU ioctl wouldn't
succeed if there was no media in the drive.

This was broken in rev 1.72 when the media check was added to cdioctl().

For now, check the ioctl group to decide whether to check for media or not.
(We only need to check for media on CD-specific ioctls.)

Reported by:	bland
MFC after:	3 days

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