feat(st-pmic): add STPMIC2 driver

The STPMIC2 embeds 15 regulators with various
properties, and is designed to supply the STM32MP2
SOC. This driver handles a minimal set of feature
to handle the boot of a board.

Signed-off-by: Pascal Paillet <p.paillet@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Maxime Méré <maxime.mere@foss.st.com>
Change-Id: Ibe0cacf8aec2871eb9a86ec16cbbd18d3745fe9e
6 files changed