mmu_notifiers: remove leftover stub macros

mmu_notifiers: remove leftover stub macros

Commit ec8832d007cb ("mmu_notifiers: don't invalidate secondary TLBs as
part of mmu_notifier_invalidate_range_end()") removed the main definitions
of {ptep,pmdp_huge,pudp_huge}_clear_flush_notify; just their
!CONFIG_MMU_NOTIFIER stubs are left behind, remove them.

Link: https://lkml.kernel.org/r/20250523-mmu-notifier-cleanup-unused-v1-1-cc1f47ebec33@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>