configs: migrate CONFIG_VIDEO_BMP_RLE8 to defconfigs

Done with:
./tools/moveconfig.py VIDEO_BMP_RLE8

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/riotboard_defconfig b/configs/riotboard_defconfig
index 4d317f6..a45d541 100644
--- a/configs/riotboard_defconfig
+++ b/configs/riotboard_defconfig
@@ -53,4 +53,5 @@
 CONFIG_VIDEO_IPUV3=y
 CONFIG_SPLASH_SCREEN=y
 CONFIG_SPLASH_SCREEN_ALIGN=y
+CONFIG_VIDEO_BMP_RLE8=y
 CONFIG_OF_LIBFDT=y