Fix KeyError exception if no model name
Fix KeyError exception if no model name

Some QEMU devices lack a model name or cpu type
in the hardware context. Port change from packaging
branch to master.

Change-Id: I0a29ad286544cc2e194bff586db729e64db0c22d

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