configs/raspberrypi0w_defconfig: fix post script args

Commit ada40afb324 updated the raspberrypi*defconfigs to use
 -add-miniuart-bt-overlay instead of -add-pi3-miniuart-bt-overlay.
Update raspberrypi0w_defconfig also.

Signed-off-by: Christopher McCrory <chrismcc@gmail.com>
Reviewed-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

configs/raspberrypi0w_defconfig

@@ -29,4 +29,4 @@ BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
 # BR2_TARGET_ROOTFS_TAR is not set
 BR2_ROOTFS_POST_BUILD_SCRIPT="board/raspberrypi0w/post-build.sh"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/raspberrypi0w/post-image.sh"
-BR2_ROOTFS_POST_SCRIPT_ARGS="--add-pi3-miniuart-bt-overlay"
+BR2_ROOTFS_POST_SCRIPT_ARGS="--add-miniuart-bt-overlay"