net: dsa: bcm_sf2: Get rid of unmarshalling functions

Now that we have migrated the CFP rule handling to a list with a
software copy, the delete/get operation just returns what is on the
list, no need to read from the hardware which is both slow and more
error prone.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>