dt-bindings: qcom: Document msm8916-gplus-fl8005a

Document the new gplus,fl8005a device tree bindings used in its
device tree.

Signed-off-by: Lin, Meng-Bo <linmengbo0689@protonmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230107133158.139785-1-linmengbo0689@protonmail.com