staging: i4l: pcbit: remove duplicated include from capi.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/capi.c

@@ -27,7 +27,6 @@
  *              encode our number in CallerPN and ConnectedPN
  */
 
-#include <linux/string.h>
 #include <linux/kernel.h>
 
 #include <linux/types.h>