ide: remove IDE_*_REG macros

* Add IDE_{ALTSTATUS,IREASON,BCOUNTL,BCOUNTH}_OFFSET defines.

* Remove IDE_*_REG macros - this results in more readable
  and slightly smaller code.

There should be no functional changes caused by this patch.

Cc: Borislav Petkov <petkovbb@gmail.com>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>