scsi: qla2xxx: Cleanups for NVRAM/Flash read/write path

This patch does following:

 - Clean up NVRAM code.
 - Optimizes reading of primary/secondary flash image validation.
 - Remove 0xff mask and make correct width in FLT structure.
 - Use endian macros to assign static fields in fwdump header.
 - Correct fdwt checksum calculation.
 - Simplify ql_dump_buffer() interface usage.
 - Add endianizers to 27xx firmware image validator.
 - fixes compiler warnings for big endian architecture.

Signed-off-by: Joe Carnuccio <joe.carnuccio@cavium.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>