Coverity fixes for Zendesk issue

[rlm2002]

Description

• Unused values
  • Move res = pt->buffer inside else statement so NULL assignment is not overwritten.
• Overflowed array index
  • Set check to include any negative value. Function expects only WOLFSSL_FATAL_ERROR to be returned, but adding check in the event another error value can be returned.
• Logically dead code
  • Remove unused check, mac_alg is always 0 when iteration returns.
  • Add additional check for inLen > 2*ED448_PUB_KEY_SIZE, ensures importing uncompressed public key can be reached. Also reported by wolfSSL Coverity build (CI 299583)
• Failure to restore non-local value
  • Removes oldLen and sets a->length to 0 if keepOldData is not set. The value of a->length is not changed in other parts of the function, so it is able to be used instead of oldLen when copying oldData into new buffer. wolfSSL Coverity Project CID 315966

Addresses Coverity issues from zd#20212

[rlm2002]

retest this please Jenkins
PRB-fipsv2-regression-and-rolling-release-v3 - Cannot contact wolf-linux-cloud-node-e7fikn: java.io.IOException: cannot find current thread
wolf-linux-cloud-node-d6ugn1 has been removed for 5 min 0 sec; assuming it is not coming back, and terminating shell step. Issue occurs in:
PRB-valgrind-check-v3
PRB-fips-repo-and-harness-test-v3-part1
PRB-multi-test-script
PRB-140-3-tests
PRB-generic-config-parser

[rlm2002]

retest this please jenkins: PRB-multi-test-script - Found unhandled hudson.remoting.RequestAbortedException exception:
java.io.StreamCorruptedException: invalid stream header: 636F7272

[rlm2002]

retest this please Jenkins - PRB-aarch64-tests-v2: Error cloning remote repo 'origin'
Caused by: hudson.plugins.git.GitException: Command "git init /var/lib/jenkins/workspace/PRB-aarch64-tests-v2" returned status code 137