Silence warnings related to "control reaches end of non-void function"

Move ERROR macros out of default branches in switch statements, to the
end of the function.

Signed-off-by: Matthew Bentham <Matthew.Bentham@arm.com>
Change-Id: I66d47eb0f2fc0a3ab4bf2dd4a01d8b0907786c98
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/2709
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Pablo Marquez <pablo.tello@arm.com>
Reviewed-by: Sang-Hoon Park <sang-hoon.park@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/runtime/SchedulerFactory.cpp b/src/runtime/SchedulerFactory.cpp
index 8bdd510..63a130d 100644
--- a/src/runtime/SchedulerFactory.cpp
+++ b/src/runtime/SchedulerFactory.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019 ARM Limited.
+ * Copyright (c) 2019-2020 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -74,9 +74,9 @@
         }
         default:
         {
-            ARM_COMPUTE_ERROR("Invalid Scheduler type");
             break;
         }
     }
+    ARM_COMPUTE_ERROR("Invalid Scheduler type");
 }
 } // namespace arm_compute