RSE: Tests: Add ECDSA signature validation tests

Add ECDSA signature validation functionality and tests to the existing
RSE provisioning test suite. Initially this verifies the provisioning
flow where the ROTPK is in the ROM.

Change-Id: I16e3eb235dba8463c44f120fa3f31ccd62f5a1bb
Signed-off-by: Jackson Cooper-Driver <jackson.cooper-driver@arm.com>
4 files changed