arm64: dts: qcom: sdm845-tama: Add regulator-system-load to l14a/l28a

Add the properties to ensure the ever so delicate touchscreen setup
matches downstream.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230313-topic-tama_disp-v3-3-2b1567c039d7@linaro.org