feat(dnn/opencl): add heuristic rule for elemwise

GitOrigin-RevId: 2bc574b5a73883356cbb468d2f025a9f6ced0d06

tools/gen_header_for_bin_reduce.py

@@ -185,7 +185,7 @@ class HeaderGen:
         ).stdout.decode('utf-8')
         self._fout.write('// midout \n')
         self._fout.write(cvt)
-        if cvt.find(" half,"):
+        if cvt.find(" half,") > 0:
             change = open(self._fout.name).read().replace(" half,", " __fp16,")
             with open("fix_fp16_bin_reduce.h", "w") as fix_fp16:
                 fix_fp16.write(change)