megaraid_sas: fix a small problem when reading state value from hw

When the driver reads state values from the hw it might happen that
different values are read in subsequent reads and this can cause problems,
this may lead to a timeout in this function and a non working adapter.

Cc: Adam Radford <aradford@gmail.com>
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Reviewed-by: Shintaro Minemoto <fj3207hq@aa.jp.fujitsu.com>
Acked-by: Sumit Saxena <sumit.saxena@lsi.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>