dt-bindings: Use portable sort for version cmp

sort -C is like sort -c >/dev/null but less portable. It fails on
busybox sort (i.e alpine linux).

Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Fixes: ea5b8b5e ("dt-bindings: Add a minimum version check for dtschema")
Link: https://lore.kernel.org/r/20210201165829.58656-1-iskren.chernev@gmail.com


Signed-off-by: Rob Herring <robh@kernel.org>