gen_test_keys.sh: Fixup key_index when keys already exist

BRANCH=none
BUG=chromium:684354
TEST=rm tests/testkeys/key_rsa2048*; make genkeys -j8

Change-Id: I6c75d2d54faf7a02c8fc4ef1ccc8647809c1aae8
Reviewed-on: https://chromium-review.googlesource.com/438949
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
1 file changed