mm/huge_memory.c: fix used-uninitialized

Fix used-uninitialized of `page'.

Fixes: dce7d10b ("mm/madvise: optimize lazyfreeing with mTHP in madvise_free")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406260514.SLhNM9kQ-lkp@intel.com


Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>