Document the compatible for pm7250b that is used with e.g. sm6350.

Also while we're at it, sort the compatibles alphabetically.
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220902111055.106814-1-luca.weiss@fairphone.com