[media] cx23885: Fix some smatch warnings

Make sure that it won't go past the config buffers

	drivers/media/pci/cx23885/cx23885-dvb.c:1733 dvb_register() warn: buffer overflow 'netup_xc5000_config' 2 <= s32max
	drivers/media/pci/cx23885/cx23885-dvb.c:1745 dvb_register() warn: buffer overflow 'netup_stv0367_config' 2 <= s32max
	drivers/media/pci/cx23885/cx23885-dvb.c:1752 dvb_register() warn: buffer overflow 'netup_xc5000_config' 2 <= s32max
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/pci/cx23885/cx23885-dvb.c

@@ -1720,6 +1720,9 @@ static int dvb_register(struct cx23885_tsport *port)
 		}
 		break;
 	case CX23885_BOARD_NETUP_DUAL_DVB_T_C_CI_RF:
+		if (port->nr > 2)
+			return 0;
+
 		i2c_bus = &dev->i2c_bus[0];
 		mfe_shared = 1;/* MFE */
 		port->frontends.gate = 0;/* not clear for me yet */

drivers/media/pci/cx23885/cx23885.h

@@ -257,7 +257,7 @@ struct cx23885_dmaqueue {
 struct cx23885_tsport {
 	struct cx23885_dev *dev;
 
-	int                        nr;
+	unsigned                   nr;
 	int                        sram_chno;
 
 	struct vb2_dvb_frontends   frontends;