arm64: dts: qcom: msm8996: remove bogus ufs_variant node

This ufs_variant node seems to be a remnant from downstream devicetree.

As it doesn't seem to be used by anything upstream, remove it from the
dtsi.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221012215613.32054-1-luca@z3ntu.xyz