GPU_matrix: use Blender's naming conventions

Thanks to @sergey for review

source/blender/editors/interface/view2d.c

@@ -1151,7 +1151,7 @@ void UI_view2d_view_restore(const bContext *C)
 	int height = BLI_rcti_size_y(&ar->winrct) + 1;
 
 	wmOrtho2(0.0f, (float)width, 0.0f, (float)height);
-	gpuLoadIdentity();
+	GPU_matrix_identity_set();
 
 	//	ED_region_pixelspace(CTX_wm_region(C));
 }