ide: unify conversion macros

Introduce to_ide_drv() and ide_drv_g() macros and replace the respective
definitions of similar ones in each driver.

There should be no functionality change resulting from this patch.

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