nfp: fix TLV offset calculation

The data pointer in the config space TLV parser already includes
NFP_NET_CFG_TLV_BASE, it should not be added again. Incorrect
offset values were only used in printed user output, rendering
the bug merely cosmetic.

Fixes: 73a0329b ("nfp: add TLV capabilities to the BAR")
Signed-off-by: Edwin Peer <edwin.peer@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>