DT schema expects TLMM pin configuration nodes to be named with
'-state' suffix and their optional children with '-pins' suffix.

Merge subnodes named 'pinconf' and 'pinmux' into one entry, add function
where missing (required by bindings for GPIOs) and reorganize overriding
pins by boards.

Split the SPI and UART configuration into separate nodes
1. SPI (MOSI, MISO, SCLK), SPI chip-select, SPI chip-select via GPIO,
2. UART per each pin: TX, RX and optional CTS/RTS.

This allows each board to customize them easily without adding any new
nodes.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221020225135.31750-4-krzysztof.kozlowski@linaro.org