drm/bridge: tc358767: Drop custom tc_write()/tc_read() accessors

A very unfortunate aspect of tc_write()/tc_read() macro helpers is
that they capture quite a bit of context around them and thus require
the caller to have magic variables 'ret' and 'tc' as well as label
'err'. That makes a number of code paths rather counter-intuitive and
somewhat clunky, for example tc_stream_clock_calc() ends up being like
this:

	int ret;

	tc_write(DP0_VIDMNGEN1, 32768);

	return 0;
err:
	return ret;

which is rather surprising when you read the code for the first
time. Since those helpers arguably aren't really saving that much code
and there's no way of fixing them without making them too verbose to
be worth it change the driver code to not use them at all.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Andrey Gusakov <andrey.gusakov@cogentembedded.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Cory Tusar <cory.tusar@zii.aero>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190619052716.16831-6-andrew.smirnov@gmail.com