Fix logic for signing with input digest smaller than key size

[dgarske]

• Fixed logic for signing with input digest smaller than key size. ZD 19869
• Improved input digest size logic for TPM2_Sign and TPM2_Verify.
• Added test case for ECC sign/verify with various digest input sizes.
• Exposed TPM2_ASN_TrimZeros.
• Fixed test_TPM2_PCRSel test.

[embhorn]

I am seeing a failure with the new test

ERROR - tests/unit_tests.c line 432 failed with:
    expected: rc == 0
    result:   707(0x2c3) != 0(0x0)

RPi3 with SLB9670

[dgarske]

I am seeing a failure with the new test

ERROR - tests/unit_tests.c line 432 failed with:
    expected: rc == 0
    result:   707(0x2c3) != 0(0x0)

RPi3 with SLB9670

It does not support ECC384. Let me resolve that with a run-time detection.

[embhorn]

Great, tests are passing now