Fix minor mistakes in v2 CSR generation

1. I parsed the wrong key. Now parsing the MACed key.
2. Construction of v1 CSR was incorrect, fixed.
3. Bail when a HAL is unsupported (was getting NPE).
4. Improved logging.
5. Use /data/local/tmp instead of primary user storage.

Bug: 280836832
Test: RkpRegistrationCheck.sh on Pixel 6
Merged-In: I308654f434de37158be483b6b6a433d7985d35e8
Change-Id: I308654f434de37158be483b6b6a433d7985d35e8