mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

Commit 20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for
movable-dedicated node") has introduced CONFIG_MOVABLE_NODE without a
good explanation on why it is actually useful.

It makes a lot of sense to make movable node semantic opt in but we
already have that because the feature has to be explicitly enabled on
the kernel command line.  A config option on top only makes the
configuration space larger without a good reason.  It also adds an
additional ifdefery that pollutes the code.

Just drop the config option and make it de-facto always enabled.  This
shouldn't introduce any change to the semantic.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Acked-by: Reza Arbab <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Yasuaki Ishimatsu <[email protected]>
Cc: Xishi Qiu <[email protected]>
Cc: Kani Toshimitsu <[email protected]>
Cc: Chen Yucong <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Daniel Kiper <[email protected]>
Cc: Igor Mammedov <[email protected]>
Cc: Vitaly Kuznetsov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>