FROMLIST: BACKPORT: maple_tree: Move mas_wr_end_piv() below mas_wr_extend_null()

Relocate it and call mas_wr_extend_null() from within mas_wr_end_piv().
Extending the NULL may affect the end pivot value so call
mas_wr_endtend_null() from within mas_wr_end_piv() to keep it all
together.

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

Link: https://lore.kernel.org/lkml/20230601021605.2823123-12-Liam.Howlett@oracle.com/


[surenb: moved additional wr_mas->end_piv assignment missing in later
kernel versions]

Bug: 274059236
Change-Id: I55c5843273e7a679aef918e66d4b4ed034d493da
Signed-off-by: Suren Baghdasaryan <surenb@google.com>