tpm: infrastructure for TPM spaces

Added an ability to virtualize TPM commands into an isolated context
that we call a TPM space because the word context is already heavily
used in the TPM specification. Both the handle areas and bodies (where
necessary) are virtualized.

The mechanism works by adding a new parameter struct tpm_space to the
tpm_transmit() function. This new structure contains the list of virtual
handles and a buffer of page size (currently) for backing storage.

When tpm_transmit() is called with a struct tpm_space instance it will
execute the following sequence:

1. Take locks.
2. Load transient objects from the backing storage by using ContextLoad
   and map virtual handles to physical handles.
3. Perform the transaction.
4. Save transient objects to backing storage by using ContextSave and
   map resulting physical handle to virtual handle if there is such.

This commit does not implement virtualization support for hmac and
policy sessions.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: James Bottomley <James.Bottomley@HansenPartnership.com>