tigertool: Migrate tigertool.py to python2/3 compatible
tigertool: Migrate tigertool.py to python2/3 compatible

BUG=chromium:1031705
BRANCH=master
TEST=None

Signed-off-by: kerker <b60348db21a0b73e8345c1da67719faa1d4da16e@chromium.org>
Change-Id: I50b9aa6724bc6d9db5c7f743909d81c0b2dfc849
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2431319
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Reviewed-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec