soc: rockchip: grf: Set pwm2/xin32k pad default to xin32k for rk3368

soc: rockchip: grf: Set pwm2/xin32k pad default to xin32k for rk3368

PWM2 and xin32k share the same pad, but some peripheral need the xin32k
clock to run properly, such as tsadc. I have observed that this pad is
used as xin32k by default on some existing board [1], so it maybe more
appropriate to set it to xin32k by default.

I also tested it on another rk3368 based board [2], without this adjust,
tsadc does not work properly.

[1] https://rockchip.fr/geekbox/Geekbox_V1.23.pdf
[2] https://ieiao.github.io/wiki/embedded-dev/rockchip/rk3368

Signed-off-by: WeiHao Li <cn.liweihao@gmail.com>
Link: https://patch.msgid.link/20250906142125.7602-1-cn.liweihao@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>