The SoC/board bindings for i.MX1/31/35 are undocumented. Add the missing
bindings to the schema.

Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>