tpm: tpm_spapr: Exit on TPM backend failures

tpm: tpm_spapr: Exit on TPM backend failures

Exit on TPM backend failures in the same way as the TPM CRB and TIS device
models do. With this change we now get an error report when the backend
did not start up properly:

error: internal error: qemu unexpectedly closed the monitor:
2020-07-07T12:49:28.333928Z qemu-system-ppc64: tpm-emulator: \
  TPM result for CMD_INIT: 0x101 operation failed

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20200707201625.4177419-2-stefanb@linux.vnet.ibm.com
(cherry picked from commit f8b332a1ff107dc014a52eaf9bf547995205f18a)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>