nfp: move filling ring information to FW config

nfp_net_[rt]x_ring_{alloc,free} should only allocate or free
ring resources without touching the device.  Move setting
parameters in the BAR to separate functions.  This will make
it possible to reuse alloc/free functions to allocate new
rings while the device is running.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>