Coverity: parameter checking and NULL assignment

[rlm2002]

Description

Adds length check against MAX_OID_SZ in wc_oid_sum(), returns 0 if length exceeds MAX_OID_SZ.

• Addresses multiple untrusted loop bounds.

Assigns p2 to NULL before next loop iteration.

• Resource leak issue.

Remove most NULL assignments intest_wolfSSL_ASN1_TIME_adj()

• unused value

Testing

make check

Checklist

• [ ] added tests
• [ ] updated/added doxygen
• [ ] updated appropriate READMEs
• [ ] Updated manual and documentation