tpm: access command header through struct in tpm_try_transmit()

Instead of accessing fields of the command header through offsets to
the raw buffer, it is a better idea to use the header struct pointer
that is already used elsewhere in the function.
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: Alexander Steffen <Alexander.Steffen@infineon.com>

drivers/char/tpm/tpm-interface.c

@@ -187,8 +187,8 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, struct tpm_space *space,
 	if (bufsiz > TPM_BUFSIZE)
 		bufsiz = TPM_BUFSIZE;
 
-	count = be32_to_cpu(*((__be32 *) (buf + 2)));
-	ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
+	count = be32_to_cpu(header->length);
+	ordinal = be32_to_cpu(header->ordinal);
 	if (count == 0)
 		return -ENODATA;
 	if (count > bufsiz) {