tpm: move wait_for_tpm_stat() to respective driver files

The function wait_for_tpm_stat() is currently defined in
tpm-interface file. It is a hardware specific function used
only by tpm_tis and xen-tpmfront, so it is removed from
tpm-interface.c and defined in respective driver files.

Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>