ivi-homescreen bbappends need update

With the ivi-homescreen SRCREV floating in meta-flutter, the ivi-homescreen bbappends in meta-agl-flutter are currently broken by the upstream change to replace the '-a' option with '-b'.  This can be fixed by updating the definition IVI_HOMESCREEN_APP_OVERRIDE in meta-agl-devel/meta-agl-flutter/recipes-graphics/toyota/ivi-homescreen_aglflutter.inc, but it does maybe raise the question of whether ivi-homescreen should not be left floating (either upstream or in our bbappends).  @Joel Winarske, should we go ahead and update IVI_HOMESCREEN_APP_OVERRIDE ourselves, or do you have any updates planned for meta-agl-flutter that would include that?