tpm/st33zp24: Fix spelling mistake in macro ST33ZP24_TISREGISTER_UKNOWN

Fix spelling mistake, rename ST33ZP24_TISREGISTER_UKNOWN to
ST33ZP24_TISREGISTER_UNKNOWN

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>