[PATCH] ide: move CONFIG_IDE_MAX_HWIFS into linux/ide.h

CONFIG_IDE_MAX_HWIFS is a generic thing, no need to have it duplicated
by every arch that uses it.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>