ramips: dts: add 'broken-cd' for VoCore2 MMC
This model doesn't have cd pin on its MicroSD card slot.
Fixes: https://github.com/openwrt/openwrt/issues/20288
Fixes: https://github.com/openwrt/openwrt/issues/22603
Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/21568
Signed-off-by: Hauke Mehrtens <[email protected]>