Revert "image_signing: use sparse partition extraction"
Revert "image_signing: use sparse partition extraction"

This reverts commit 82dec09bd5098715ddf9cd7d2e4abe87606d5249.

This flag doesn't exist on Ubuntu Precise which is what the signers
are running atm.  Until we get them upgraded to Trusty, back this
change out.

BUG=chromium:530730
TEST=`./signing_unittests.py` passes
BRANCH=None

Change-Id: I9ba508c1531dbb169fd020d06ab102f6576b7342
Reviewed-on: https://chromium-review.googlesource.com/306310
Commit-Ready: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Reviewed-by: Amey Deshpande <62824f2effac1e9cdf0924b4b6823fc05b5ab6be@google.com>

coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot