Hob: Set one of deployable images or runnable images as the default toggled item

Hob: Set one of deployable images or runnable images as the default toggled item

With this patch, even though there are a lot of images built out, a default image
which is either deployable or runnable is toggled by default. So, for users, one
more action to select an image before running qemu or deploying is not needed any more.

Note: If there are more than one runnable or deployable images (such as ext2, ext3,
jffs2 and btrfs), only the first image is toggled by default for run-qemu or
deployment. If the user wants to run or deploy others, he/she needs to toggle them
manually.

[Yocto #2155]

(Bitbake rev: 4568dfbd5e693cce0e6e947f323eaf08a3176744)

Signed-off-by: Shane Wang <shane.wang@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>