Always use Fermat's Little Theorem in ecdsa_sign_setup. am: c5f118738a am: 424cd02670 am: f40f1ba20b am: 44720342df  -s ours am: 432b1ecc99
am: 60102fdb0b

Change-Id: I8f3e7ea53adc4ce94e27a0db432b9bf860976d4b