mm: ptep_clear_flush_range_notify() macro for batch operation

We will soon add support for CoWing large anonymous folios, so create a
ranged version of the ptep_clear_flush_notify() macro in preparation for
that. It is able call mmu_notifier_invalidate_range() once for the
entire range, but still calls ptep_clear_flush() per page since there is
no arch support for a batched version of this API yet.

No functional change intended.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>