arm64: dts: qcom: msm8998: Allow UFSHC driver to set-load

The UFS host controller driver needs to set the load on 3 power rails
(l20, l26, s4) but the operation fails silently unless we specify the
regulator-allow-set-load property in the corresponding DT nodes.

Tested-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Signed-off-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>