staging: vt6656: fix bad symbol declaration

With sparse, the following error appears :
  CHECK   drivers/staging/vt6656/aes_ccmp.c
drivers/staging/vt6656/aes_ccmp.c:221:6: warning: symbol 'AESbGenCCMP' was not declared. Should it be static?

Add correct include header in order to have function declaration.

Signed-off-by: Neil 'Superna' Armstrong <superna9999@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>