tpm: remove unnecessary #ifdef CONFIG_TPM

Makefile.objs now checks for $(CONFIG_TPM).

Suggested-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
