This patch (from Alan Stern as157) fixes the non-READ/WRITE paths of the
sddr09.c driver to be compliant to the requirements of scatter-gather.  It
also cleans up MODE_SENSE processing and reports errors a little better.

This patch also makes MODE_SENSE_10 commands report an error.  The old code
claimed to support both 6- and 10-byte versions, but really only supported
6-byte.   Bad data was returned for the 10-byte case, so it was removed.  A
patch to follow in a few minutes fixes this.