dt-bindings: msm: dsi-phy-28nm: Document msm8226 compatible

dt-bindings: msm: dsi-phy-28nm: Document msm8226 compatible

The MSM8226 SoC uses a slightly different 28nm dsi phy. Add a new
compatible for it.

And while we're at it, in the dsi-phy-28nm.yaml move the 8960 compatible
to its correct place so its sorted alphabetically.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Patchwork: https://patchwork.freedesktop.org/patch/540621/
Link: https://lore.kernel.org/r/20230308-msm8226-mdp-v3-1-b6284145d67a@z3ntu.xyz
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>