Remove unnecessary HID functionality (#243)

* Include HID report functionality only when the HID feature is enabled
* Define HID_CONTROLS=1 so HID unit tests work correctly

lib_xua/src/hid/hid_report.c

@@ -1,5 +1,7 @@
 // Copyright 2021-2022 XMOS LIMITED.
 // This Software is subject to the terms of the XMOS Public Licence: Version 1.
+#if( 0 < HID_CONTROLS )
+
 #include <assert.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -851,3 +853,5 @@ unsigned hidReportValidate( void )
         return hidReportValidateInfoStruct( &info );
     }
 }
+
+#endif // ( 0 < HID_CONTROLS )