mm: remove CONFIG_UNEVICTABLE_LRU config option

mm: remove CONFIG_UNEVICTABLE_LRU config option

Currently, nobody wants to turn UNEVICTABLE_LRU off.  Thus this
configurability is unnecessary.

Signed-off-by: KOSAKI Motohiro <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Andi Kleen <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Matt Mackall <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Lee Schermerhorn <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>