arm64: dts: qcom: sc8280xp-x13s: add pmic regulator supplies

The s11b, s12b, s1c and bob supplies are used by several pmic
regulators. Add the missing description to the devicetree.

Note that there are still some consumers that are not (fully) described
in the devicetree so the supplies must remain marked as always-on for
now.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230322113318.17908-6-johan+linaro@kernel.org