mm/mmu_gather: clean up the stale code comment

mm/mmu_gather: clean up the stale code comment

In commit d7f861b9c43a ("mm/mmu_gather: add __tlb_remove_folio_pages()"),
helper function __tlb_remove_folio_pages_size() was added.  And based on
the helper, wrapper functions __tlb_remove_folio_pages() and
__tlb_remove_page_size() are created and used by upper level functions.

So let's update the code comment to reflect the current code about
tlb_remove_page()/tlb_remove_page_size(), etc.

Link: https://lkml.kernel.org/r/20250211034348.39531-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>