rde1edge/run_model: remove default virtio image selection for busybox

Do not default to a virtio image for busybox filesystem. The -v
parameter is expected to set the virtio disk image to be used.

Change-Id: Id566f8a5699c989113360c40e7c047e3ccb41463
Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>

rdinfra/platforms/rde1edge/run_model.sh

@@ -196,10 +196,6 @@ if [[ -z $FIP_IMAGE ]]; then
 	FIP_IMAGE="fip-uefi.bin";
 fi
 
-if [[ ${FS_TYPE,,} == "busybox" ]]; then
-	VIRTIO_IMAGE_PATH="${ROOTDIR}/grub-busybox.img"
-fi
-
 if [[ -n "$VIRTIO_IMAGE_PATH" ]]; then
 	MODEL_PARAMS="$MODEL_PARAMS \
 			-C board.virtioblockdevice.image_path=${VIRTIO_IMAGE_PATH}"