Correct a rare stale RAID map access when performing AIO during a RAID
configuration change.

A race condition in the driver could cause it to access a stale RAID map
when a logical volume is reconfigured.

Modify the driver logic to invalidate a RAID map very early when a RAID
configuration change is detected and only switch to a new RAID map after
the driver detects that the RAID map has changed.

Link: https://lore.kernel.org/r/165730606128.177165.7671413443814750829.stgit@brunhildaReviewed-by: NScott Benesh <scott.benesh@microchip.com>
Reviewed-by: NScott Teel <scott.teel@microchip.com>
Reviewed-by: NMike McGowen <mike.mcgowen@microchip.com>
Signed-off-by: NKevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: NDon Brace <don.brace@microchip.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>