xtensa, kasan: define KASAN_SHADOW_END

Common KASAN code might rely on the definitions of the shadow mapping
start, end, and size.  Define KASAN_SHADOW_END in addition to
KASAN_SHADOW_START and KASAN_SHADOW_SIZE.

Link: https://lkml.kernel.org/r/20231225151924.5422-1-andrey.konovalov@linux.dev


Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312240755.MqsWuTno-lkp@intel.com/


Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>