ide-floppy: convert to generic packet commands

Replace the ide-floppy packet commands opcode defines with the generic ones.
Add a missing GPCMD_WRITE_12 (opcode 0xaa) to the generic ones in cdrom.h. The
last one can be found in the current version of INF-8090, p.905.

[ Bart: Tejun's libata patch also adding GPCMD_WRITE_12 got merged first ]

Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>