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
4a367f3a 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>