Check main disk is fixed in hardware_SsdDetection

This CL checks /sys/block/[DEVICE]/removable to make sure that
main disk is fixed in hardware_SsdDetection test.
This is required by partner that we should test more properties of eMMC.

BUG=None
TEST=run hardware_SsdDetection on DUT. I have tested it on snow board and
lumpy and can pass the test.
We plan to test eMMC with hdparm in the future.

Change-Id: I7ab5005866cd4a12189aad18a48c55b6c1df2de4
Reviewed-on: https://gerrit.chromium.org/gerrit/24008
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: Cheng-Yi Chiang <cychiang@chromium.org>
1 file changed