dt-bindings: Improve phandle-array schemas

The 'phandle-array' type is a bit ambiguous. It can be either just an
array of phandles or an array of phandles plus args. Many schemas for
phandle-array properties aren't clear in the schema which case applies
though the description usually describes it.

The array of phandles case boils down to needing:

items:
  maxItems: 1

The phandle plus args cases should typically take this form:

items:
  - items:
      - description: A phandle
      - description: 1st arg cell
      - description: 2nd arg cell

With this change, some examples need updating so that the bracketing of
property values matches the schema.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Georgi Djakov <djakov@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20220119015038.2433585-1-robh@kernel.org