staging:dgnc: Replace printk by pr_warn

This patch replaces printk with pr_warn as the printk calls are used to
display warnings to remove the checkpatch.pl warnings:
WARNING: printk() should include KERN_ facility level
and then WARNING: Prefer netdev_warn(netdev, ... then dev_warn(dev,
... then pr_warn(...  to printk(KERN_WARNING ... on adding KERN_WARNING
message designation.
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgnc/dgnc_driver.c

@@ -236,7 +236,7 @@ int dgnc_init_module(void)
 		if (dgnc_NumBoards)
 			pci_unregister_driver(&dgnc_driver);
 		else
-			printk("WARNING: dgnc driver load failed.  No Digi Neo or Classic boards found.\n");
+			pr_warn("WARNING: dgnc driver load failed.  No Digi Neo or Classic boards found.\n");
 
 		dgnc_cleanup_module();
 	}