rv110x: OpenWRT compatibility fixes

[rgrizzell]

• nvmem/rockchip-otp: enable add_legacy_fixed_of_cells so OTP cells are accessible via the legacy fixed-of-cells interface used by OpenWRT
• soc/rockchip/Makefile: remove duplicate pm_domains.o build entry; the driver was moved to drivers/pmdomain/ in 6.5, building both causes "Driver 'rockchip-pm-domain' is already registered" at boot
• include/linux/extcon.h: add EXTCON_USB_VBUS_EN constant (value 3), required by phy-rockchip-inno-usb2.c for USB gadget VBUS control
• sound/soc/rockchip/rockchip_i2s_tdm.c: add rv1106 match entry with no soc_data (same as vendor 5.10 kernel); without this the i2s driver never binds and asoc-simple-card loops on -EPROBE_DEFER

[rgrizzell]

@plan44 Thanks for merging the OpenWRT changes. I'd like to merge some 6.6.93 changes into another mainline branch for us to use. I named this one openwrt-rv110x-6.6.93 following the same pattern.

OpenWrt 25.12.2 uses Linux 6.12 which should include all of the Rockchip changes by default. At that point, we should be able to revert back to patch files and won't have to update this fork.

[plan44]

@rgrizzell

OpenWrt 25.12.2 uses Linux 6.12 which should include all of the Rockchip changes by default

Are you sure? Has the upstream situation changed very recently? The mainline kernel did not have any support for the small rv110x rockchips at all, only a few months ago (the rk3xxxx were supported for a while already). I'd be happy to learn that mainline rv110x support is no longer a dream!

[rgrizzell]

@rgrizzell

OpenWrt 25.12.2 uses Linux 6.12 which should include all of the Rockchip changes by default

Are you sure? Has the upstream situation changed very recently? The mainline kernel did not have any support for the small rv110x rockchips at all, only a few months ago (the rk3xxxx were supported for a while already). I'd be happy to learn that mainline rv110x support is no longer a dream!

I'm not for sure certain, but Claude had mentioned it in passing when reviewing the OnionIoT commits on your fork of their fork.

I'll look into it and confirm.

Edit: I couldn't find any mainline commits. Feels like hallucinations or a scan of the vendor fork. Sorry for the misinformation.