ARC: west runner: mdb-hw: fix incorrect argument handling for jtag

Currently we just pass in case of the unsupported jtag adapter
is selected. Fix that by rising ValueError as we do in case of
other incorrect arguments.

While I'm at it add few missing test-cases for mdb west runners.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>