eth: fbnic: allocate unreadable page pool for the payloads

eth: fbnic: allocate unreadable page pool for the payloads

Allow allocating a page pool with unreadable memory for the payload
ring (sub1). We need to provide the queue ID so that the memory provider
can match the PP. Use the appropriate page pool DMA sync helper.
For unreadable mem the direction has to be FROM_DEVICE. The default
is BIDIR for XDP, but obviously unreadable mem is not compatible
with XDP in the first place, so that's fine. While at it remove
the define for page pool flags.

The rxq_idx is passed to fbnic_alloc_rx_qt_resources() explicitly
to make it easy to allocate page pools without NAPI (see the patch
after the next).

Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250901211214.1027927-12-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>