COMPMID-2826 Comply with DCL51-CPP

Rename all header guards to be compliant with DCL51-CPP

Change-Id: I47b09375bb1b8d39d80c275ce69a3f25fb385d75
Signed-off-by: Michalis Spyrou <micspy01@e123758.cambridge.arm.com>
Reviewed-on: https://review.mlplatform.org/c/2393
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/graph/GraphContext.h b/arm_compute/graph/GraphContext.h
index 0eb9e81..973264a 100644
--- a/arm_compute/graph/GraphContext.h
+++ b/arm_compute/graph/GraphContext.h
@@ -21,8 +21,8 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-#ifndef __ARM_COMPUTE_GRAPH_GRAPH_CONTEXT_H__
-#define __ARM_COMPUTE_GRAPH_GRAPH_CONTEXT_H__
+#ifndef ARM_COMPUTE_GRAPH_GRAPH_CONTEXT_H
+#define ARM_COMPUTE_GRAPH_GRAPH_CONTEXT_H
 
 #include "arm_compute/graph/Types.h"
 
@@ -131,4 +131,4 @@
 };
 } // namespace graph
 } // namespace arm_compute
-#endif /* __ARM_COMPUTE_GRAPH_GRAPH_CONTEXT_H__ */
+#endif /* ARM_COMPUTE_GRAPH_GRAPH_CONTEXT_H */