arm64: dts: qcom: pm8998: Add a specific compatible for coincell chg

Add a PM8998-specific compatible to the coincell charger and keep the
PM8941 one as fallback.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230214090849.2186370-3-konrad.dybcio@linaro.org