trivial: NULL noise: drivers/media/dvb/frontends/drx397xD_fw.h

Fix this sparse warnings:
  drivers/media/dvb/frontends/drx397xD_fw.h:21:2: warning: Using plain integer as NULL pointer
  drivers/media/dvb/frontends/drx397xD_fw.h:22:2: warning: Using plain integer as NULL pointer

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/media/dvb/frontends/drx397xD.c

@@ -74,7 +74,7 @@ static struct {
 } fw[] = {
 #define _FW_ENTRY(a, b, c)	{					\
 			.name	= a,					\
-			.file	= 0,					\
+			.file	= NULL,					\
 			.lock	= __RW_LOCK_UNLOCKED(fw[c].lock),	\
 			.refcnt = 0,					\
 			.data	= { }		}