eth: fbnic: move xdp_rxq_info_reg() to resource alloc

eth: fbnic: move xdp_rxq_info_reg() to resource alloc

Move rxq_info and mem model registration from fbnic_alloc_napi_vector()
and fbnic_alloc_nv_resources() to fbnic_alloc_rx_qt_resources().
The rxq_info is now registered later in the process, but that
should not cause any issues.

rxq_info lives in the fbnic_q_triad (qt) struct so qt init is a more
natural place. Encapsulating the logic in the qt functions will also
allow simplifying the cleanup in the NAPI related alloc functions
in the next commit.

Rx does not have a dedicated fbnic_free_rx_qt_resources(),
but we can use xdp_rxq_info_is_reg() to tell whether given
rxq_info was in use (effectively - if it's a qt for an Rx queue).

Having to pass nv into fbnic_alloc_rx_qt_resources() is not
great in terms of layering, but that's temporary, pp will
move soon..

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250901211214.1027927-3-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>