Rename is_MSB_are_same() to mpt3sas_check_same_4gb_region() for better
readability.

Link: https://lore.kernel.org/r/1587626596-1044-3-git-send-email-suganath-prabu.subramani@broadcom.comReviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Suganath Prabu <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>