drm/bridge: tc358768: Fix use of uninitialized variable

smatch reports:

drivers/gpu/drm/bridge/tc358768.c:223 tc358768_update_bits() error: uninitialized symbol 'orig'.

Fix this by bailing out from tc358768_update_bits() if the
tc358768_read() produces an error.

Fixes: ff1ca639 ("drm/bridge: Add tc358768 driver")
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Tested-by: Maxim Schwalm <maxim.schwalm@gmail.com> # Asus TF700T
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230906-tc358768-v4-2-31725f008a50@ideasonboard.com

drivers/gpu/drm/bridge/tc358768.c

@@ -216,6 +216,10 @@ static void tc358768_update_bits(struct tc358768_priv *priv, u32 reg, u32 mask,
 	u32 tmp, orig;
 
 	tc358768_read(priv, reg, &orig);
+
+	if (priv->error)
+		return;
+
 	tmp = orig & ~mask;
 	tmp |= val & mask;
 	if (tmp != orig)