tpm xen: Remove bogus tpm_chip_unregister

BugLink: http://bugs.launchpad.net/bugs/1654602

commit 1f0f30e4 upstream.

tpm_chip_unregister can only be called after tpm_chip_register.
devm manages the allocation so no unwind is needed here.

Fixes: afb5abc2 ("tpm: two-phase chip management functions")
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/char/tpm/xen-tpmfront.c

@@ -305,7 +305,6 @@ static int tpmfront_probe(struct xenbus_device *dev,
 	rv = setup_ring(dev, priv);
 	if (rv) {
 		chip = dev_get_drvdata(&dev->dev);
-		tpm_chip_unregister(chip);
 		ring_free(priv);
 		return rv;
 	}