tpm: cr50: Support opening the TPM multiple times

The tpm_auto_start() function is used in tests and assumes that it can
open the TPM even if it is already open and a locality claimed. The cr50
driver does not use the common TPM2 TIS code so lacks a check for the
is_open field of struct tpm_chip and in fact it doesn't use that struct.

Add an equivalent check to cr50_i2c_open().

This fixes tpm_auto_start() on coral.

Series-to: u-boot

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/tpm/cr50_i2c.c

@@ -737,9 +737,13 @@ static int cr50_i2c_report_state(struct udevice *dev, char *str, int str_max)
 
 static int cr50_i2c_open(struct udevice *dev)
 {
+	struct cr50_priv *priv = dev_get_priv(dev);
 	char buf[80];
 	int ret;
 
+	if (priv->locality != -1)
+		return -EBUSY;
+
 	ret = process_reset(dev);
 	if (ret)
 		return log_msg_ret("reset", ret);