Commit 8e11d62e2e87 ("powerpc/mem: Add back missing header to fix 'no
previous prototype' error") was supposed to fix the problem, but in
the meantime commit a927bd6ba952 ("mm: fix phys_to_target_node() and*
memory_add_physaddr_to_nid() exports") moved create_section_mapping()
prototype from asm/sparsemem.h to asm/mmzone.h