maple_tree: Remove smp_wmb() from mas_wmb_replace()

maple_tree: Remove smp_wmb() from mas_wmb_replace()

Since nodes now reused the pivots for tracking other dead nodes, the
smp_wmb() needed to be called sooner.  Remove the later call and rename
the mas_wmb_replace() function to mas_cleanup_replace() since it no
longer calls any write memory barriers.

This is an optimization fix for the maple tree.

Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>