gve: Update QPL page registration logic

gve: Update QPL page registration logic

For DQO, change QPL page registration logic to be more flexible to honor
the "max_registered_pages" parameter from the gVNIC device.

Previously the number of RX pages per QPL was hardcoded to twice the
ring size, and the number of TX pages per QPL was dictated by the device
in the DQO-QPL device option. Now [in DQO-QPL mode], the driver will
ignore the "tx_pages_per_qpl" parameter indicated in the DQO-QPL device
option and instead allocate up to (tx_queue_length / 2) pages per TX QPL
and up to (rx_queue_length * 2) pages per RX QPL while keeping the total
number of pages under the "max_registered_pages".

Merge DQO and GQI QPL page calculation logic into a unified
gve_update_num_qpl_pages function. Add rx_pages_per_qpl to the priv
struct for consumption by both DQO and GQI.

Signed-off-by: Matt Olson <maolson@google.com>
Signed-off-by: Max Yuan <maxyuan@google.com>
Reviewed-by: Jordan Rhee <jordanrhee@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
Link: https://patch.msgid.link/20260225182342.1049816-2-joshwash@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>