[PATCH] dvb: fix NULL pointer dereference when loading the budget-av module

Ralph Metzler wrote:
> AFAIR, there is a bug in tda10021.c in tda10021_readreg() which
> references state->frontend.dvb->num
> This is fatal if the frontend is not at the probed address and thus
> not yet registered (no dvb entry set yet -> NULL pointer ...).

The attached patch should get rid of the oops.

Signed-off-by: Jon Burgess <jburgess@uklinux.net>
Cc: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>