runqueue: report progress for "Preparing RunQueue" step

runqueue: report progress for "Preparing RunQueue" step

When "Preparing RunQueue" shows up you can expect to wait up to 30
seconds while it works - which is a bit long to leave the user waiting
without any kind of output. Since the work being carried out during this
time is divided into stages such that it's practical to determine
internally how it's progressing, replace the message with a progress
bar.

Actually what happens during this time is two major steps rather than
just one - the runqueue preparation itself, followed by the
initialisation prior to running setscene tasks. I elected to have the
progress bar cover both as one (there doesn't appear to be much point in
doing otherwise from a user perspective). I did however describe it as
"initialising tasks".

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>