[PATCH] ide-cd: quiet down GPCMD_READ_CDVD_CAPACITY failure

Some drives like to throw a:

ATAPI device hdc:
  Error: Not ready -- (Sense key=0x02)
  Incompatible medium installed -- (asc=0x30, ascq=0x00)
  The failed "Read Cd/Dvd Capacity" packet command was:
  "25 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 "

warning on incompatible media, so quiet down this error.

Signed-off-by: Jens Axboe <axboe@suse.de>