FROMLIST: maple_tree: Reduce resets during store setup

mas_prealloc() may walk partially down the tree before finding that a
split or spanning store is needed.  When the write occurs, relax the
logic on resetting the walk so that partial walks will not restart, but
walks that have gone too far (a store that affects beyond the current
node) should be restarted.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>

Link: https://lore.kernel.org/all/20230612203953.2093911-16-Liam.Howlett@oracle.com/


Bug: 274059236
Change-Id: I87dedebae085f067b08caeaf1bd19bb343ff305f
Signed-off-by: Suren Baghdasaryan <surenb@google.com>