drivers/i2c/tpm: Fix blank default statement

CB:59479 introduced a blank default statement. This is treated as an
error or warning on some older toolchains. Add a break statement on
default case.

BUG=None
TEST=Build the Guybrush mainboard.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Change-Id: I3d034cfebc8b8ae7d7024d41b4b2207cdeb083e8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59551
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Patrick Georgi <patrick@coreboot.org>
Reviewed-by: Rob Barnes <robbarnes@google.com>

src/drivers/i2c/tpm/chip.c

@@ -60,6 +60,7 @@ static void i2c_tpm_fill_ssdt(const struct device *dev)
 	case TPM_DEFAULT_POWER_MANAGED:
 	default:
 		/* Leave firmware-power-managed unset */
+		break;
 	}
 	acpi_dp_write(dsd);