drm: tilcdc: don't use devm_pinctrl_get_select_default() in probe

Since commit ab78029e ("drivers/pinctrl: grab default handles from
device core"), we can rely on device core for setting the default pins.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230922073714.6164-1-wsa+renesas@sang-engineering.com