Add check to prevent testing crypto home perf on USB stick.

TEST=Check test ends in NA if booted on usb stick
Check test works as expected when using the fixed device.

BUG=chromium:372952

Change-Id: I799dd869dd54135dfd907a82017be047bce4fd0e
Reviewed-on: https://chromium-review.googlesource.com/204485
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Commit-Queue: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
1 file changed