dt-bindings: msm/dsi: Add qcm2290 dsi controller binding

Add DSI block specific qcm2290 compatible string as valid
Qualcomm DSI controller.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/474090/
Link: https://lore.kernel.org/r/1644853060-12222-3-git-send-email-loic.poulain@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>