Always use Fermat's Little Theorem in ecdsa_sign_setup. am: 5e7ef724ae am: c30b290833 am: 7a6d3ea6eb am: 210bab9a05 am: 1e87d30042  -s ours
am: 3ae941ed08

Change-Id: I72cb82dcb56ef7a4175753e00bf2dfd9095876c3