ide-floppy: convert driver to the new debugging macro

Also:

- leave in the possibility for optimizing away all debugging macros
- add a PFX macro and prepend all printk calls with it for consistency
- change idefloppy_create_rw_cmd's 1st arg from idefloppy_floppy_t * to
ide_drive_t *.
- add a missing printk-level in idefloppy_init
- fix minor checkpatch warnings

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>