Support multiple xml_config files in ServoTest class.

By changing the args xml_config in Servo to be a list.

BUG=chromium-os:19710,chrome-os-partner:5966
TEST=run_remote_tests.sh --remote=$REMOTE_IP -a \
     "xml_config=servo_x86-alex_overlay.xml servo_vid=0x18d1 servo_pid=0x5001" \
     firmware_DevMode

Change-Id: I0b62953b8c55e6972c27452720d7f2f34ab6397a
Reviewed-on: https://gerrit.chromium.org/gerrit/11114
Reviewed-by: Todd Broch <tbroch@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
2 files changed