tty: hvcs: Drop unnecessary if block

If hvcs_probe() succeeded dev_set_drvdata() is called with a non-NULL
value, and if hvcs_probe() failed hvcs_remove() isn't called.

So there is no way dev_get_drvdata() can return NULL in hvcs_remove() and
the check can just go away.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>