[media] cx24120: Update comment & fix typo

These state vars are used for more than just ber calculation, also
fix typo.

Signed-off-by: Jemma Denson <jdenson@gmail.com>
Signed-off-by: Patrick Boettcher <patrick.boettcher@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/dvb-frontends/cx24120.c

@@ -150,7 +150,7 @@ struct cx24120_state {
 
 	fe_status_t fe_status;
 
-	/* ber stats calulations */
+	/* dvbv5 stats calculations */
 	u32 bitrate;
 	u32 berw_usecs;
 	u32 ber_prev;