ui/crumbs/tasklistmodel: fix saving recipes

After switching to dynamically finding the relative path for the recipe
file it's no longer to append .bb when inserting the require line into the
saved recipe.

Fixes [YOCTO #1247]

(Bitbake rev: 2d05ce4f527daa905ed64485029ebeb2b349daa6)

Signed-off-by: Joshua Lock <josh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>