mm: fix outdated incorrect code comments for handle_mm_fault()

[akpm@linux-foundation.org: s/mmap_Lock/mmap_lock/, per Liam]
Link: https://lkml.kernel.org/r/20241213031820.778342-1-alexjlzheng@tencent.com


Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>