net: dsa: bcm_sf2: Fix IP fragment location and behavior

The IP fragment is specified through user-defined field as the first
bit of the first user-defined word. We were previously trying to extract
it from the user-defined mask which could not possibly work. The ip_frag
is also supposed to be a boolean, if we do not cast it as such, we risk
overwriting the next fields in CFP_DATA(6) which would render the rule
inoperative.

Fixes: 7318166c

 ("net: dsa: bcm_sf2: Add support for ethtool::rxnfc")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>