dt-bindings: leds: qcom-lpg: Narrow nvmem for other variants

Only few variants support PPG and store LPG per-channel data and pattern
in SDAM modules.  Disallow the nvmem for other variants to make the
binding precise.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240226073713.19045-2-krzysztof.kozlowski@linaro.org


Signed-off-by: Lee Jones <lee@kernel.org>