kernel: fortify: Hide run-time copy size from value range tracking

kernel: fortify: Hide run-time copy size from value range tracking

Fix compilation warning treated as an error:
./include/linux/fortify-string.h:114:33: error: '__builtin_memcpy' reading between 65 and 536870904 bytes from a region of size 64 [-Werror=stringop-overread]
  114 | #define __underlying_memcpy     __builtin_memcpy
      |                                 ^
./include/linux/fortify-string.h:633:9: note: in expansion of macro '__underlying_memcpy'
  633 |         __underlying_##op(p, q, __fortify_size);                        \
      |         ^~~~~~~~~~~~~
./include/linux/fortify-string.h:678:26: note: in expansion of macro '__fortify_memcpy_chk'
  678 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
      |                          ^~~~~~~~~~~~~~~~~~~~
./include/linux/bitmap.h:259:17: note: in expansion of macro 'memcpy'
  259 |                 memcpy(dst, src, len);
      |                 ^~~~~~
kernel/padata.c: In function '__padata_set_cpumasks':
kernel/padata.c:735:48: note: source object 'pcpumask' of size [0, 64]
  735 |                                  cpumask_var_t pcpumask,
      |                                  ~~~~~~~~~~~~~~^~~~~~~~

Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=239d87327dcd361b0098038995f8908f3296864f
Signed-off-by: Mieczyslaw Nalewaj <namiltd@yahoo.com>
Link: https://github.com/openwrt/openwrt/pull/16547
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>