xsk: advance cq/fq check when shared umem is used

xsk: advance cq/fq check when shared umem is used

In the shared umem mode with different queues or devices, either
uninitialized cq or fq is not allowed which was previously done in
xp_assign_dev_shared(). The patch advances the check at the beginning
so that 1) we can avoid a few memory allocation and stuff if cq or fq
is NULL, 2) it can be regarded as preparation for the next patch in
the series.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
Link: https://patch.msgid.link/20260104012125.44003-2-kerneljasonxing@gmail.com
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>