Fail, don't assert, if unable to create context
Fail, don't assert, if unable to create context

As the "do we have any usable devices?" check uses this,
it needs to not crash even when we don't.

Signed-off-by: Rebecca N. Palmer <2decb937e7eca5e941ec22bc308fd452fe4ab2bb@zoho.com>
Reviewed-by: Yang Rong <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet