ide: move IDE{FLOPPY,TAPE}_WAIT_CMD defines to <linux/ide.h>

While at it:

* IDE{FLOPPY,TAPE}_WAIT_CMD -> WAIT_{FLOPPY,TAPE}_CMD

* Use enum for WAIT_* defines.

There should be no functional changes caused by this patch.

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