pnp: set the pnp_card dma_mask for use by ISAPnP cards

dma_alloc_coherent() on x86 currently takes a passed in NULL device
pointer to mean that it should allocate an ISA compatible (24-bit) buffer
which is a bit of a hack.

The ALSA ISA drivers are the main consumers of this but have a struct
device in fact readily available.

For the PnP drivers, the specific pnp_dev->dev device pointer is not
always available at the right time so for now we want to pass the
pnp_card->dev instead which is always available.  Set its dma_mask in
preparation for doing so.

This does not fix a current bug -- 2.6.26-rc1 stumbled over the NULL hack
in dma_alloc_coherent() but this has already been fixed in commit
4a367f3a9dbf2e7ffcee4702203479809236ee6e by Takashi Iwai.

Signed-off-by: Rene Herman <rene.herman@gmail.com>
Acked-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/pnp/card.c

@@ -8,6 +8,7 @@
 #include <linux/ctype.h>
 #include <linux/slab.h>
 #include <linux/pnp.h>
+#include <linux/dma-mapping.h>
 #include "base.h"
 
 LIST_HEAD(pnp_cards);
@@ -167,6 +168,9 @@ struct pnp_card *pnp_alloc_card(struct pnp_protocol *protocol, int id, char *pnp
 	sprintf(card->dev.bus_id, "%02x:%02x", card->protocol->number,
 		card->number);
 
+	card->dev.coherent_dma_mask = DMA_24BIT_MASK;
+	card->dev.dma_mask = &card->dev.coherent_dma_mask;
+
 	dev_id = pnp_add_card_id(card, pnpid);
 	if (!dev_id) {
 		kfree(card);