configs: migrate CONFIG_BMP_16/24/32BPP to defconfigs

Done with:
./tools/moveconfig.py BMP_16BPP BMP_24BPP BMP_32BPP

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/pico-imx6_defconfig b/configs/pico-imx6_defconfig
index da00167..b08fa5f 100644
--- a/configs/pico-imx6_defconfig
+++ b/configs/pico-imx6_defconfig
@@ -91,3 +91,4 @@
 CONFIG_SPLASH_SCREEN=y
 CONFIG_SPLASH_SCREEN_ALIGN=y
 CONFIG_VIDEO_BMP_RLE8=y
+CONFIG_BMP_16BPP=y