usbip: vudc: Make use of the helper macro LIST_HEAD()

Replace "struct list_head head = LIST_HEAD_INIT(head)" with
"LIST_HEAD(head)" to simplify the code.

LIST_HEAD() helps to clean up the code "struct list_head vudc_devices =",
only to care about the variable 'vudc_devices'.

Reviewed-by: Shuah Khan <[e-mail]>
Signed-off-by: Cai Huoqing <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/usbip/vudc_main.c

···
 	},
 };
 
-static struct list_head vudc_devices = LIST_HEAD_INIT(vudc_devices);
+static LIST_HEAD(vudc_devices);
 
 static int __init init(void)
 {