staging: dgap: fix overflows and format strings

The boot message buffer could potentially overflow the stack and the
heap. Additionally make sure format strings could not leak into printk()
calls.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/staging/dgap/dgap_driver.c
Simple merge