pinctrl: mediatek: paris: Skip custom extra pin config dump for virtual GPIOs

Virtual GPIOs do not have any hardware state associated with them. Any
attempt to read back hardware state for these pins result in error
codes.

Skip dumping extra pin config information for these virtual GPIOs.

Fixes: 184d8e13

 ("pinctrl: mediatek: Add support for pin configuration dump via debugfs.")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220308100956.2750295-7-wenst@chromium.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>