media: si2157: add support for DVB-C Annex C

DVB-C Annex C is mostly DVB-C Annex A with only minor differences, so
simply add it to the DVB-C Annex A switch case, so that tuning attempts
no longer result in -EINVAL.

Link: https://lore.kernel.org/linux-media/trinity-fd7dd9e4-c319-4761-89b6-555fa7b23776-1641509569422@3c-app-gmx-bap68
Signed-off-by: Robert Schlabbach <robert_s@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Author: robert-sc

drivers/media/tuners/si2157.c

@@ -490,6 +490,7 @@ static int si2157_set_params(struct dvb_frontend *fe)
 			delivery_system = 0x20;
 			break;
 	case SYS_DVBC_ANNEX_A:
+	case SYS_DVBC_ANNEX_C:
 			delivery_system = 0x30;
 			break;
 	case SYS_ISDBT: