arm64: dts: qcom: sm6350-lena: Flatten gpio-keys pinctrl state

arm64: dts: qcom: sm6350-lena: Flatten gpio-keys pinctrl state

Pinctrl states typically collate multiple related pins.  In the case of
gpio-keys there's no hardware-defined relation at all except all pins
representing a key; and especially on Sony's lena board there's only one
pin regardless. Flatten it similar to other boards [1].

As a drive-by fix, clean up the label string.

[1]: https://lore.kernel.org/linux-arm-msm/11174eb6-0a9d-7df1-6f06-da4010f76453@linaro.org/

Fixes: 2b8bbe985659 ("arm64: dts: qcom: sm6350-lena: Include pm6350 and configure buttons")
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221222215906.324092-1-marijn.suijten@somainline.org