tpm: sandbox: Support self-test continue in emulator

Add support for the self-test continue command in the TPM v1.2 emulator,
to match the functionality in the TPM v2 emulator.

Change-Id: I2fad865da519b36eb7d5879bb9ab552db8055e1f
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

drivers/tpm/tpm_tis_sandbox.c

@@ -221,6 +221,7 @@ static int sandbox_tpm_xfer(struct udevice *dev, const uint8_t *sendbuf,
 	case 0x72: /* physical set deactivated */
 	case 0x99: /* startup */
 	case 0x50: /* self test full */
+	case 0x53: /* self test continue */
 	case 0x4000000a:  /* assert physical presence */
 		*recv_len = 12;
 		memset(recvbuf, '\0', *recv_len);