ALSA: hdspm - Fix uninitialized compile warnings

Put the exception checks for io_type switch() for possible mistakes in
future.  Also this shuts up annoying compile warnings.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/rme9652/hdspm.c

@@ -1339,6 +1339,10 @@ static u64 hdspm_calc_dds_value(struct hdspm *hdspm, u64 period)
 		break;
 	case MADIface:
 		freq_const = 131072000000000ULL;
+		break;
+	default:
+		snd_BUG();
+		return 0;
 	}
 
 	return div_u64(freq_const, period);
@@ -1366,6 +1370,9 @@ static void hdspm_set_dds_value(struct hdspm *hdspm, int rate)
 	case AIO:
 		n = 104857600000000ULL;  /* 100 MHz */
 		break;
+	default:
+		snd_BUG();
+		return;
 	}
 
 	n = div_u64(n, rate);