tpm: replace TPM_TRANSMIT_RAW with TPM_TRANSMIT_NESTED

As TPM_TRANSMIT_RAW always requires also not to take locks for obvious
reasons (deadlock), this commit renames the flag as TPM_TRANSMIT_NESTED
and prevents taking tpm_mutex when the flag is given to tpm_transmit().

Suggested-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>