[SCSI] qla2xxx: Export flash-block-size for application support.

In handling the RMW semantics needed to update regions not
falling on a sector boundary.

Signed-off-by: Lalit Chandivade <lalit.chandivade@qlogic.com>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>