arm64: dts: rockchip: Fix mic-in-differential usage on rk3566-roc-pc

arm64: dts: rockchip: Fix mic-in-differential usage on rk3566-roc-pc

The 'mic-in-differential' DT property supported by the RK809/RK817 audio
codec driver is actually valid if prefixed with 'rockchip,':

  DTC_CHK arch/arm64/boot/dts/rockchip/rk3566-roc-pc.dtb
  rk3566-roc-pc.dtb: pmic@20: codec: 'mic-in-differential' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/mfd/rockchip,rk809.yaml#

Make use of the correct property name.

Fixes: a8e35c4bebe4 ("arm64: dts: rockchip: add audio nodes to rk3566-roc-pc")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://lore.kernel.org/r/20240622-rk809-fixes-v2-4-c0db420d3639@collabora.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>