drm: mm: add "best_match" to drm_mm_insert_node()

Add a "best_match" argument similar to the drm_mm_search_*() helpers so we
can convert TTM to use them in follow up patches.

Also move the non-generic aliases to drm_mm.h header instead of keeping
them in the source file.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm: ttm: replace drm_mm_pre_get() with direct alloc

Instead of calling drm_mm_pre_get() in a row, we now preallocate the node
and then use the atomic insertion functions. This has the exact same
semantics and there is no reason to use the racy pre-allocations.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm/i915: use preallocated nodes instead of drm_mm search/get_block

i915 is the last user of the weird search+get_block drm_mm API. Convert it
to an explicit kmalloc()+insert_node().

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm/mm: remove unused API

These calls are no longer used. Remove them.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>