ASoC: rockchip: Remove unused of_gpio.h

ASoC: rockchip: Remove unused of_gpio.h

of_gpio.h is deprecated and subject to remove. The drivers in question
don't use it, simply remove the unused header.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240605221446.2624964-4-andriy.shevchenko@linux.intel.com
Reviewed-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mark Brown <broonie@kernel.org>