thermal/drivers/mediatek: Fix control buffer enablement on MT7896

Reading thermal sensor on mt7986 devices returns invalid temperature:

bpi-r3 ~ # cat /sys/class/thermal/thermal_zone0/temp
 -274000

Fix this by adding missing members in mtk_thermal_data struct which were
used in mtk_thermal_turn_on_buffer after commit 33140e66.

Cc: stable@vger.kernel.org
Fixes: 33140e66 ("thermal/drivers/mediatek: Control buffer enablement tweaks")
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Daniel Golle <daniel@makrotopia.org>
Tested-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230907112018.52811-1-linux@fw-web.de

drivers/thermal/mediatek/auxadc_thermal.c

@@ -690,6 +690,9 @@ static const struct mtk_thermal_data mt7986_thermal_data = {
 	.adcpnp = mt7986_adcpnp,
 	.sensor_mux_values = mt7986_mux_values,
 	.version = MTK_THERMAL_V3,
+	.apmixed_buffer_ctl_reg = APMIXED_SYS_TS_CON1,
+	.apmixed_buffer_ctl_mask = GENMASK(31, 6) | BIT(3),
+	.apmixed_buffer_ctl_set = BIT(0),
 };
 
 static bool mtk_thermal_temp_is_valid(int temp)