arm64: dts: qcom: sdm845-db845c: Add pm_8998 gpio names

Add pm_8998 GPIO trace names. These names are defined in
the 96boards db845c mezzanine schematic.

Signed-off-by: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200324155843.10719-5-robert.foss@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>