Change the argument type to cl_platform_info.

Although both `cl_platform_info` and `cl_device_info` are defined as macro `cl_uint`, it needs to use `cl_platform_info` to get
the platform information.

modules/core/src/ocl.cpp

@@ -5528,7 +5528,7 @@ struct PlatformInfo::Impl
         getDevices(devices, handle);
     }
 
-    String getStrProp(cl_device_info prop) const
+    String getStrProp(cl_platform_info prop) const
     {
         char buf[1024];
         size_t sz=0;