devicetree: bindings: Remove unused 32-bit CMT bindings

Remove the 32-bit CMT compat strings to reduce maintenance burden.

It should be fine to break DT compatibility because the 32-bit
CMT DT binding was never part of any upstream DTS file.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>