[media] s921: Properly report the delivery system

Before this patch, a query for the delivery systems were
returned SYS_UNDEFINED.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb/frontends/s921.c b/drivers/media/dvb/frontends/s921.c
index 2e15f92..7652d3f 100644
--- a/drivers/media/dvb/frontends/s921.c
+++ b/drivers/media/dvb/frontends/s921.c
@@ -440,6 +440,7 @@
 
 	/* FIXME: Probably it is possible to get it from regs f1 and f2 */
 	p->frequency = state->currentfreq;
+	p->delivery_system = SYS_ISDBT;
 
 	return 0;
 }