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/sandbox_flattree_defconfig b/configs/sandbox_flattree_defconfig
index dd93167..6ee23c4 100644
--- a/configs/sandbox_flattree_defconfig
+++ b/configs/sandbox_flattree_defconfig
@@ -192,6 +192,7 @@
 CONFIG_VIDEO_SANDBOX_SDL=y
 CONFIG_OSD=y
 CONFIG_SANDBOX_OSD=y
+CONFIG_VIDEO_BMP_RLE8=y
 CONFIG_CMD_DHRYSTONE=y
 CONFIG_RSA_VERIFY_WITH_PKEY=y
 CONFIG_TPM=y