JTAG to Avalon master bridge usage

The qsys fabric alters the address between master and slave in two (sometimes three) ways:

* It subtracts the base address of the slave from the address provided by the master - so if you slave is at base address 0x4000 then byte address 0x4010 on the master will be seen as byte address 0x10 on the slave

* If the master or slave is marked as being word addressed (one of the interface properties controls this) then the fabric will shift the address to convert it to/from a byte address

* If the slave is marked as natively addressed then the fabric does all sorts of weird stuff. Native addressing is deprecated and should not be used.