fm10k: Fix error handling in fm10k_init_module()

[ Upstream commit 771a794c0a3c3e7f0d86cc34be4f9537e8c0a20c ]

A problem about modprobe fm10k failed is triggered with the following log
given:

 Intel(R) Ethernet Switch Host Interface Driver
 Copyright(c) 2013 - 2019 Intel Corporation.
 debugfs: Directory 'fm10k' with parent '/' already present!

The reason is that fm10k_init_module() returns fm10k_register_pci_driver()
directly without checking its return value, if fm10k_register_pci_driver()
failed, it returns without removing debugfs and destroy workqueue,
resulting the debugfs of fm10k can never be created later and leaks the
workqueue.

 fm10k_init_module()
   alloc_workqueue()
   fm10k_dbg_init() # create debugfs
   fm10k_register_pci_driver()
     pci_register_driver()
       driver_register()
         bus_add_driver()
           priv = kzalloc(...) # OOM happened
   # return without remove debugfs and destroy workqueue

Fix by remove debugfs and destroy workqueue when
fm10k_register_pci_driver() returns error.

Fixes: 7461fd913a ("fm10k: Add support for debugfs")
Fixes: b382bb1b3e ("fm10k: use separate workqueue for fm10k driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/ethernet/intel/fm10k/fm10k_main.c

@@ -32,6 +32,8 @@ struct workqueue_struct *fm10k_workqueue;
  **/
 static int __init fm10k_init_module(void)
 {
+	int ret;
+
 	pr_info("%s\n", fm10k_driver_string);
 	pr_info("%s\n", fm10k_copyright);
 
@@ -43,7 +45,13 @@ static int __init fm10k_init_module(void)
 
 	fm10k_dbg_init();
 
-	return fm10k_register_pci_driver();
+	ret = fm10k_register_pci_driver();
+	if (ret) {
+		fm10k_dbg_exit();
+		destroy_workqueue(fm10k_workqueue);
+	}
+
+	return ret;
 }
 module_init(fm10k_init_module);