staging: i4l: pcbit: drv: remove duplicated include from drv.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/i4l/pcbit/drv.c

@@ -27,7 +27,6 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
-#include <linux/string.h>
 #include <linux/skbuff.h>
 
 #include <linux/isdnif.h>