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 all init sequences on that TPM -- e.g 'tpm init && tpm init'
or 'tpm autostart && tpm init' used to hang

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/drivers/tpm/cr50_i2c.c b/drivers/tpm/cr50_i2c.c
index 08ec179..5b2d5cc 100644
--- a/drivers/tpm/cr50_i2c.c
+++ b/drivers/tpm/cr50_i2c.c
@@ -737,9 +737,13 @@
 
 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);