Check up front in test_devtool_deploy_target whether the tap devices
exist and skip if not. If we don't do this we get a significantly less
comprehensible error via pexpect.
(From OE-Core rev: 2258345e19efff7717fe19a5026ec55f1b6f90b6)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>