ARM: dts: imx7d-sdb: align pin config nodes with bindings

ARM: dts: imx7d-sdb: align pin config nodes with bindings

Bindings expect pin configuration nodes in pinctrl to match certain
naming and not be part of another fake node:

  imx7d-sdb-sht11.dtb: pinctrl@30330000: 'imx7d-sdb' does not match any of the regexes: 'grp$', 'pinctrl-[0-9]+'

Drop the "imx7d-sdb" wrapping node and adjust the names to have "grp"
prefix.  Diff looks big but this should have no functional impact.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>