scsi: lpfc: Fix some error codes in debugfs

If copy_from_user() or kstrtoull() fail then the correct behavior is to
return a negative error code.

Link: https://lore.kernel.org/r/YEsbU/UxYypVrC7/@mwanda
Fixes: f9bb2da ("[SCSI] lpfc 8.3.27: T10 additions for SLI4")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Dan Carpenter

drivers/scsi/lpfc/lpfc_debugfs.c

@@ -2421,7 +2421,7 @@ lpfc_debugfs_dif_err_write(struct file *file, const char __user *buf,
 	memset(dstbuf, 0, 33);
 	size = (nbytes < 32) ? nbytes : 32;
 	if (copy_from_user(dstbuf, buf, size))
-		return 0;
+		return -EFAULT;
 
 	if (dent == phba->debug_InjErrLBA) {
 		if ((dstbuf[0] == 'o') && (dstbuf[1] == 'f') &&
@@ -2430,7 +2430,7 @@ lpfc_debugfs_dif_err_write(struct file *file, const char __user *buf,
 	}
 
 	if ((tmp == 0) && (kstrtoull(dstbuf, 0, &tmp)))
-		return 0;
+		return -EINVAL;
 
 	if (dent == phba->debug_writeGuard)
 		phba->lpfc_injerr_wgrd_cnt = (uint32_t)tmp;