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

Documentation/devicetree/bindings/Makefile

@@ -10,7 +10,7 @@ DT_SCHEMA_MIN_VERSION = 2020.8.1
 PHONY += check_dtschema_version
 check_dtschema_version:
 	@{ echo $(DT_SCHEMA_MIN_VERSION); \
-	$(DT_DOC_CHECKER) --version 2>/dev/null || echo 0; } | sort -VC || \
+	$(DT_DOC_CHECKER) --version 2>/dev/null || echo 0; } | sort -Vc >/dev/null || \
 	{ echo "ERROR: dtschema minimum version is v$(DT_SCHEMA_MIN_VERSION)" >&2; false; }
 
 quiet_cmd_extract_ex = DTEX    $@