media: dt-bindings: Document MIPID02 bindings

This adds documentation of device tree for MIPID02 CSI-2 to PARALLEL
bridge.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mickael Guene <mickael.guene@st.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>