mm: unexport vmf_insert_mixed_mkwrite

vmf_insert_mixed_mkwrite is only used by the built-in DAX code.

Link: https://lkml.kernel.org/r/20240702072327.1640911-1-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory.c

@@ -2533,7 +2533,6 @@ vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
 {
 	return __vm_insert_mixed(vma, addr, pfn, true);
 }
-EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
 
 /*
  * maps a range of physical memory into the requested pages. the old