rocrtst: change const arg to non-const

In rocrtst helper_funcs.h, a function argument that gets
written to was previously incorrectly marked as const.

Change-Id: If8cc6555ebfa974b9665d9d5b93de01bb45fde2c


[ROCm/ROCR-Runtime commit: 1c6a4a55f1]

projects/rocr-runtime/rocrtst/common/helper_funcs.h

@@ -128,7 +128,7 @@ class ScopeGuard {
   __forceinline ~ScopeGuard() {
     if (!dismiss_) release_();
   }
-  __forceinline ScopeGuard& operator=(const ScopeGuard& rhs) {
+  __forceinline ScopeGuard& operator=(ScopeGuard& rhs) {
     dismiss_ = rhs.dismiss_;
     release_ = rhs.release_;
     rhs.dismiss_ = true;