tegra2: trivially enable 13 mhz crystal frequency

This is needed for upcoming Toradex Colibri T20 upstream support.
Signed-off-by: NLucas Stach <dev@lynxeye.de>
Signed-off-by: NTom Warren <twarren@nvidia.com>

arch/arm/cpu/armv7/tegra2/clock.c

@@ -1059,7 +1059,10 @@ void clock_early_init(void)
 		clock_set_rate(CLOCK_ID_CGENERAL, 600, 26, 0, 8);
 		break;
 
-	case CLOCK_OSC_FREQ_13_0:
+	case CLOCK_OSC_FREQ_13_0: /* OSC is 13Mhz */
+		clock_set_rate(CLOCK_ID_PERIPH, 432, 13, 1, 8);
+		clock_set_rate(CLOCK_ID_CGENERAL, 600, 13, 0, 8);
+		break;
 	case CLOCK_OSC_FREQ_19_2:
 	default:
 		/*