key: add tpm_send command

Add internal kernel tpm_send() command used to seal/unseal keys.

Changelog:
- replaced module_put in tpm_send() with new tpm_chip_put() wrapper
  (suggested by David Howells)
- Make tpm_send() cmd argument a 'void *' (suggested by David Howells)

Signed-off-by: David Safford <safford@watson.ibm.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>