JitArm64: Don't emit normal block exit for branch-to-self instructions

The normal block exit is redundant as the exception exit will jump out of
the block first, meaning this code is never executed.

Source/Core/Core/PowerPC/JitArm64/JitArm64_Branch.cpp

@@ -105,6 +105,7 @@ void JitArm64::bx(UGeckoInstruction inst)
     gpr.Unlock(WA);
 
     WriteExceptionExit(js.compilerPC);
+    return;
   }
 
   WriteExit(destination);