USB: mos7840: Cleanup useless header

BKL isn't anymore present into this file thus it is no necessary still include smp_lock.h.
Signed-off-by: NAlessio Igor Bogani <abogani@texware.it>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/mos7840.c

@@ -26,7 +26,6 @@
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/tty.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>