soc/nvidia/tegra124: Prevent implicit fallthrough

SOR_LINK_SPEED_G5_4 is unsupported, but it is not invalid, so it
suffices to return here instead of printing the next warning message.

Change-Id: Ifca3c52635e9a39af42e6616821d1099c43c237c
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Found-by: Coverity CID 1293137
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34293
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/soc/nvidia/tegra124/sor.c

@@ -844,6 +844,7 @@ void tegra_dc_sor_set_voltage_swing(struct tegra_dc_sor_data *sor)
 		break;
 	case SOR_LINK_SPEED_G5_4:
 		printk(BIOS_WARNING, "T124 does not support 5.4G link clock.\n");
+		return;
 	default:
 		printk(BIOS_WARNING, "Invalid sor link bandwidth: %d\n",
 			sor->link_cfg->link_bw);