tpm: fix invalid return value in pubek_show()

Return zero when tpm_buf_init() fails as we do for other functions in
tpm-sysfs.c.

Fixes: da379f3c ("tpm: migrate pubek_show to struct tpm_buf")
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-sysfs.c

@@ -47,9 +47,8 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 
 	memset(&anti_replay, 0, sizeof(anti_replay));
 
-	rc = tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
-	if (rc)
-		return rc;
+	if (tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK))
+		return 0;
 
 	tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));