remove extra function call. handle show(None) for framebuffer and epaper

Author: FoamyGuy

shared-module/displayio/Display.c

@@ -142,7 +142,7 @@ void common_hal_displayio_display_construct(displayio_display_obj_t *self,
 
 bool common_hal_displayio_display_show(displayio_display_obj_t *self, displayio_group_t *root_group) {
     if (root_group == NULL) {
-        return displayio_display_core_set_root_group(&self->core, &circuitpython_splash);
+        root_group = &circuitpython_splash;
     }
     return displayio_display_core_set_root_group(&self->core, root_group);
 }

shared-module/displayio/EPaperDisplay.c

@@ -103,6 +103,9 @@ void common_hal_displayio_epaperdisplay_construct(displayio_epaperdisplay_obj_t
 }
 
 bool common_hal_displayio_epaperdisplay_show(displayio_epaperdisplay_obj_t *self, displayio_group_t *root_group) {
+    if (root_group == NULL) {
+        root_group = &circuitpython_splash;
+    }
     return displayio_display_core_set_root_group(&self->core, root_group);
 }
 

shared-module/framebufferio/FramebufferDisplay.c

@@ -102,6 +102,9 @@ void common_hal_framebufferio_framebufferdisplay_construct(framebufferio_framebu
 }
 
 bool common_hal_framebufferio_framebufferdisplay_show(framebufferio_framebufferdisplay_obj_t *self, displayio_group_t *root_group) {
+    if (root_group == NULL) {
+        root_group = &circuitpython_splash;
+    }
     return displayio_display_core_set_root_group(&self->core, root_group);
 }