qcom: add support for SPMI PMICs found on SM8550 platforms

The SM8550 based platforms sports a bunch of new PMICs:
- pm8550
- pm8550b
- pm8550ve
- pm8550vs
- pmk8550
- pmr735d
- pm8010

With GPIO support on:
- pm8550
- pm8550b
- pm8550ve
- pm8550vs
- pmk8550
- pmr735d

This documents bindings for those SPMI PMIC and adds compatible in the
PMIC pinctrl driver for GPIO support.

To: Andy Gross <agross@kernel.org>
To: Bjorn Andersson <andersson@kernel.org>
To: Konrad Dybcio <konrad.dybcio@somainline.org>
To: Lee Jones <lee@kernel.org>
To: Rob Herring <robh+dt@kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
To: Stephen Boyd <sboyd@kernel.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

---
Changes in v3:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v2: https://lore.kernel.org/r/20221114-narmstrong-sm8550-upstream-spmi-v2-0-b839bf2d558a@linaro.org

Changes in v2:
- Squashed patch 3 & 2 into 1, added Reviewed-by from Krzysztof
- Squashed patch 5 into 4, added Reviewed-by from Krzysztof
- Squashed patch 7 into 6, added Reviewed-by from Konrad
- Link to v1: https://lore.kernel.org/r/20221114-narmstrong-sm8550-upstream-spmi-v1-0-6338a2b4b241@linaro.org

--- b4-submit-tracking ---
# This section is used internally by b4 prep for tracking purposes.
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    "revision": 3,
    "change-id": "20221114-narmstrong-sm8550-upstream-spmi-d2c999ec5dc1",
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    "history": {
      "v1": [
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