arm64: dts: qcom: msm8996-mtp: Add msm8996 compatible

Add qcom,msm8996 compatible to match DT schema.

Signed-off-by: Yassine Oudjana <y.oudjana@protonmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220203072226.51482-3-y.oudjana@protonmail.com