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.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210114175718.137483-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>