kconfig: allow "hex" and "range" to support longs

The parsing routines for Kconfig files use strtol(), but store and
render values as int. Switch types and formating to long to support a
wider range of values. For example, 0x80000000 wasn't representable.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>