maple_tree: check for MA_STATE_BULK on setting wr_rebalance

It is possible for a bulk operation (MA_STATE_BULK is set) to enter the
new_end < mt_min_slots[type] case and set wr_rebalance as a store type. 
This is incorrect as bulk stores do not rebalance per write, but rather
after the all of the writes are done through the mas_bulk_rebalance()
path.  Therefore, add a check to make sure MA_STATE_BULK is not set before
we return wr_rebalance as the store type.

Also add a test to make sure wr_rebalance is never the store type when
doing bulk operations via mas_expected_entries()

This is a hotfix for this rc however it has no userspace effects as there
are no users of the bulk insertion mode.

Link: https://lkml.kernel.org/r/20241011214451.7286-1-sidhartha.kumar@oracle.com


Fixes: 5d659bbb ("maple_tree: introduce mas_wr_store_type()")
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Sidhartha <sidhartha.kumar@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>