[media] radio-miropcm20: fix sparse NULL pointer warning

Fixes the following sparse warnings:

drivers/media/radio/radio-miropcm20.c:193:33: warning:
Using plain integer as NULL pointer

Signed-off-by: Wei Yongjun <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/radio/radio-miropcm20.c

···
 	freql = freq & 0xff;
 	freqh = freq >> 8;
 
-	rds_cmd(aci, RDS_RESET, 0, 0);
+	rds_cmd(aci, RDS_RESET, NULL, 0);
 	return snd_aci_cmd(aci, ACI_WRITE_TUNE, freql, freqh);
 }