atapi: cleanup/fix mode sense results The first two bytes (after the 8-byte ATAPI header) are the mode page number and the number of bytes after the length field itself. Make this clear in the code. The AUDIO_CTL page was filled with wrong values. It is not anymore in MMC, but at least keep the values sane. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>