drivers/usb/typec/tps6598x.c: fix 4CC cmd write

Writing 4CC commands with tps6598x_write_4cc() already has
a pointer arg, don't reference it when using as arg to
tps6598x_block_write(). Correcting this enforces the constness
of the pointer to propagate to tps6598x_block_write(), so add
the const qualifier there to avoid the warning.

Fixes: 0a4c005b

 ("usb: typec: driver for TI TPS6598x USB Power Delivery controllers")
Signed-off-by: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>