mm/vmalloc: remove map_kernel_range

Patch series "mm/vmalloc: cleanup after hugepage series", v2.

Christoph pointed out some overdue cleanups required after the huge
vmalloc series, and I had another failure error message improvement as
well.

This patch (of 5):

This is a shim around vmap_pages_range, get rid of it.

Move the main API comment from the _noflush variant to the normal variant,
and make _noflush internal to mm/.

Link: https://lkml.kernel.org/r/20210322021806.892164-1-npiggin@gmail.com
Link: https://lkml.kernel.org/r/20210322021806.892164-2-npiggin@gmail.com


Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>