CHANGELOG.md: Update for 1.4.0 release.
CHANGELOG.md: Update for 1.4.0 release.

This is a cherry-pick of 5a580d470262323f3764158c999e3144b89a6dd2 from
the 1.x branch with minor fixups to retain the 'Unreleased' bits.

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

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