usb: Auto-load cdc_acm module when device opened.

The cdc_acm module is missing the char-major-166-* alias that would
cause it to be auto-loaded when a device of that type is opened.  This
patch adds the alias.
Signed-off-by: NScott James Remnant <scott@canonical.com>
Signed-off-by: NTim Gardner <tim.gardner@canonical.com>
Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/usb/class/cdc-acm.c

@@ -1493,4 +1493,4 @@ module_exit(acm_exit);
 MODULE_AUTHOR( DRIVER_AUTHOR );
 MODULE_DESCRIPTION( DRIVER_DESC );
 MODULE_LICENSE("GPL");
-
+MODULE_ALIAS_CHARDEV_MAJOR(ACM_TTY_MAJOR);