Replace lava-tool with lavacli

Replace lava-tool with lavacli

In order to move totally to lavacli, this patch:
- Apply changes to submit jobs using lavacli. As the blocking call
(--block) no longer exists with lavacli, so had to replace that with
a polling loop.
- Replace lava-tool with lavacli in the polling part in the labs-prepare
file, which checks the device status and availability.

Different changes tested at Baylibre.

Change-Id: I25b1ad4b47ae09a158e1e1cf42e30da5e6aa8b57
Signed-off-by: Khouloud Touil <ktouil@baylibre.com>