sample: Fix memory leak in TpmHmac.
sample: Fix memory leak in TpmHmac.

Nearly identical to 9b8bf53c5a8476cf54c251ce9dac305de27077d6

Signed-off-by: Philip Tricca <fd418754d31777cf39b16b99b0350486ab840079@intel.com>

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