Ensure the board check uses the name of the Type
Ensure the board check uses the name of the Type

all_devices will always return None if asked for
the object, ensure that we look up the DeviceType.name
string instead. Restores the ability to submit
multinode jobs.

Change-Id: Id96b42d1b3e4b501abccd01aefdaf1a2696b47fa

Linaro/lava-server,Linaro/lava-server,Linaro/lava-server,OSSystems/lava-server,OSSystems/lava-server,OSSystems/lava-server,Linaro/lava-server