sysapi_util: Remove InitSysContext and TeardownSysContext helpers
sysapi_util: Remove InitSysContext and TeardownSysContext helpers

These functions have been declared as part of the SAPI for years but
were never _declared_ as part of the SAPI, only as part of test code.

The defintions of these functions in the test code were removed as part
of the 2.0 release, so there's no reason to keep their declarations.

See: https://github.com/tpm2-software/tpm2-tss/issues/331#issuecomment-280378592

Signed-off-by: Joe Richey <24d3dd8348b5cac19a417e52b4f8141ba91506f0@google.com>

01org/tpm2-tss,01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/TPM2.0-TSS,01org/tpm2-tss,01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/tpm2-tss,tpm2-software/tpm2-tss,01org/TPM2.0-TSS