riscv: dts: canaan: Disable I/O devices unless used

It is considered good practice to disable on-SoC devices providing
external I/O in the SoC-specific .dtsi, and enable them explicitly in
the board-specific DTS files when actually wired-up and used.

Hence:
  - Set the status of I/O devices in k210.dtsi to "disabled",
  - Override the status of used I/O devices in board-specific DTS files
    to "okay",
  - Drop unneeded status overrides in board DTS-specific files for the
    always-enabled pin controller.

On e.g. MAiXBiT, this gets rid of an error message when probing the
unused slave-only spi2 controller:

    dw_spi_mmio 50240000.spi: error -22: problem registering spi host
    dw_spi_mmio 50240000.spi: probe with driver dw_spi_mmio failed with error -22

which is seen since commit 98d75b9e ("spi: dw: Drop default
number of CS setting").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>