ide: fix pmac breakage

Fix breakage added in the IDE devel tree.

Add header, then fix

drivers/ide/ppc/pmac.c: In function `pmac_ide_setup_dma':
drivers/ide/ppc/pmac.c:2044: warning: assignment from incompatible pointer type
drivers/ide/ppc/pmac.c: In function `pmac_ide_dma_host_on':
drivers/ide/ppc/pmac.c:1989: warning: control reaches end of non-void function
include/linux/pci.h: In function `pmac_ide_init':
drivers/ide/ppc/pmac.c:1563: warning: ignoring return value of `pci_register_driver', declared with attribute warn_unused_result

Then add some apparently-long-missing error handling.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>