dt-bindings: display/msm: dsi-controller-main: Add msm8226 compatible

Add the compatible for the DSI found on MSM8226.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Patchwork: https://patchwork.freedesktop.org/patch/540613/
Link: https://lore.kernel.org/r/20230308-msm8226-mdp-v3-2-b6284145d67a@z3ntu.xyz


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>