AP_Param: added AP_PARAM_NO_SHIFT

used for cases where we know the shift is not needed

libraries/AP_Param/AP_Param.cpp

@@ -114,7 +114,7 @@ void AP_Param::erase_all(void)
 */
 uint32_t AP_Param::group_id(const struct GroupInfo *grpinfo, uint8_t base, uint8_t i, uint8_t shift)
 {
-    if (grpinfo[i].idx == 0 && shift != 0) {
+    if (grpinfo[i].idx == 0 && shift != 0 && !(grpinfo[i].flags & AP_PARAM_NO_SHIFT)) {
         /*
           this is a special case for a bug in the original design. An
           idx of 0 shifted by n bits is still zero, which makes it

libraries/AP_Param/AP_Param.h

@@ -46,6 +46,10 @@
 // invisible
 #define AP_PARAM_FLAG_ENABLE        4
 
+// don't shift index 0 to index 63. Use this when you know there will be
+// no conflict with the parent
+#define AP_PARAM_NO_SHIFT           8
+
 // a variant of offsetof() to work around C++ restrictions.
 // this can only be used when the offset of a variable in a object
 // is constant and known at compile time