KeyMint vts: Correct the EC curve parameter and some return code

Strongbox doens't support p-224. Change the curve to p-256 for better
compatibility.
Also update the tags to be filtered on the hw-enforcement list.

Bug: 186735514
Test: VtsAidlKeyMintTargetTest
Change-Id: I3f587c5471ca68b88a565ee9ec2e27d1e9e11b17
Merged-In: Ia8eb4c8e28810de5f37295abd8baed6f01b19a3c