usb/early: remove unused including <linux/version.h>

Fix the following versioncheck warning:

drivers/usb/early/xhci-dbc.c:21:1: unused including <linux/version.h>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20200421033945.27703-1-yanaijie@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/early/xhci-dbc.c

@@ -18,7 +18,6 @@
 #include <asm/fixmap.h>
 #include <linux/bcd.h>
 #include <linux/export.h>
-#include <linux/version.h>
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>