Add qtmultimedia radio plugin to demo images

Add qtmultimedia radio plugin to demo images

Add qtmultimedia-rtlfm-radio-plugin recipe and add it as a dependency
of the CES 2017 demo so it will go into the demo images.  It is required
for the Radio application.

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I764c561a8a7c864ac98240bb2f54995d29ce0934