mm/vmalloc: fix typo in local variable name

In __purge_vmap_area_lazy(), rename local_pure_list to local_purge_list.

Link: https://lkml.kernel.org/r/20220607105958.382076-4-bhe@redhat.com


Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>