autotest server: skip size check if encrypted stateful path is unavailable

Encrypted stateful may not be enabled on all boards, so if
/mnt/stateful_partition/encrypted doesn't exist, skip size
check.

BUG=chromium:386310
TEST=./server/autoserver --reset -m <dut> passes against a gizmo build.
TEST=./server/autoserver --reset -m <dut> passes against a gizmo build
     with /mnt/stateful_partition/encrypted existing on the dut

Change-Id: I1d2788f9b38ccc71ea441da42ee5bb779b4d2d90
Reviewed-on: https://chromium-review.googlesource.com/204792
Reviewed-by: Richard Barnette <jrbarnette@chromium.org>
Tested-by: Gaurav Shah <gauravsh@chromium.org>
Commit-Queue: Gaurav Shah <gauravsh@chromium.org>
1 file changed