tpm: ibmvtpm: simplify crq initialization and document crq format

The crq is passed in registers and is the same on BE and LE hosts.
However, current implementation allocates a structure on-stack to
represent the crq, initializes the members swapping them to BE, and
loads the structure swapping it from BE. This is pointless and causes
GCC warnings about ununitialized members. Get rid of the structure and
the warnings.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>