lkdtm/bugs: fix build error in lkdtm_EXHAUST_STACK

lkdtm/bugs: fix build error in lkdtm_EXHAUST_STACK

lkdtm/bugs.c:94:2: error: format '%d' expects argument of type 'int', but argument 2 has type 'long unsigned int' [-Werror=format=]
  pr_info("Calling function with %d frame size to depth %d ...\n",
  ^
THREAD_SIZE is defined as a unsigned long, cast CONFIG_FRAME_WARN to
unsigned long as well.

Fixes: 24cccab42c419 ("lkdtm/bugs: Adjust recursion test to avoid elision")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20190827173619.170065-1-rrangel@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>