Converting firmware_DevBootUSB to use new FirmwareTest class.

The new FirmwareTest class does not require the traditional dict of objects
that FAFTSequence required.

1. Converted the test to use the new flat function call style.

BUG=chromium:371185
TEST=Manually ran this test at desk against peppy device.

Change-Id: I681181790eeea940ad9cdbe8caac5afd2615cf46
Reviewed-on: https://chromium-review.googlesource.com/200346
Reviewed-by: Wai-Hong Tam <waihong@chromium.org>
Commit-Queue: Yusuf Mohsinally <mohsinally@chromium.org>
Tested-by: Yusuf Mohsinally <mohsinally@chromium.org>
1 file changed