MLECO-2684: Standardize LCD behaviour

* LCD display behavior for Run All now matches Run Next
* Remove repeated code

Signed-off-by: Richard Burton <richard.burton@arm.com>
Change-Id: I16706187fd4e7a59dd935783f5bfb8731435f381
diff --git a/source/use_case/ad/src/UseCaseHandler.cc b/source/use_case/ad/src/UseCaseHandler.cc
index b20b63e..bc6ec7a 100644
--- a/source/use_case/ad/src/UseCaseHandler.cc
+++ b/source/use_case/ad/src/UseCaseHandler.cc
@@ -68,8 +68,6 @@
         constexpr uint32_t dataPsnTxtInfStartX = 20;
         constexpr uint32_t dataPsnTxtInfStartY = 40;
 
-        platform.data_psn->clear(COLOR_BLACK);
-
         auto& model = ctx.Get<Model&>("model");
 
         /* If the request has a valid size, set the audio index */
@@ -114,6 +112,8 @@
         auto audioDataStride = nMelSpecVectorsInAudioStride * frameStride;
 
         do {
+            platform.data_psn->clear(COLOR_BLACK);
+
             auto currentIndex = ctx.Get<uint32_t>("clipIndex");
 
             /* Get the output index to look at based on id in the filename. */