docs: dt: submitting-patches: add commit subject prefix in reversed format

ASoC, media, regulators and SPI subsystems prefer commits starting with
subsystem name (e.g. "spi: dt-bindings:"), so document this to avoid
confusing contributors.

Cc: Mark Brown <broonie@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240108083750.16350-2-krzysztof.kozlowski@linaro.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/submitting-patches.rst

@@ -15,6 +15,11 @@ I. For patch submitters
 
        "dt-bindings: <binding dir>: ..."
 
+     Few subsystems, like ASoC, media, regulators and SPI, expect reverse order
+     of the prefixes::
+
+       "<binding dir>: dt-bindings: ..."
+
      The 80 characters of the subject are precious. It is recommended to not
      use "Documentation" or "doc" because that is implied. All bindings are
      docs. Repeating "binding" again should also be avoided.