dt-bindings: display/msm: dsi-controller-main: Add missing minItems

dt-bindings: display/msm: dsi-controller-main: Add missing minItems

Specific constrain in if:then: blocks for variable lists, like clocks
and clock-names, should have a fixed upper and lower size.  Older
dtschema implied minItems, but that's not true since 2024 and missing
minItems means that lower bound is not set.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/638751/
Link: https://lore.kernel.org/r/20250221-b4-sm8750-display-v3-2-3ea95b1630ea@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>