Merge branch 'sfc-tx-queues'

Íñigo Huguet says:

====================
sfc: Fix lack of XDP TX queues

A change introduced in commit dad6c821dff0 ("sfc: reduce the number of
requested xdp ev queues") created a bug in XDP_TX and XDP_REDIRECT
because it unintentionally reduced the number of XDP TX queues, letting
not enough queues to have one per CPU, which leaded to errors if XDP
TX/REDIRECT was done from a high numbered CPU.

This patchs make the following changes:
- Fix the bug mentioned above
- Revert commit be95fea3a160 ("sfc: adjust efx->xdp_tx_queue_count with
  the real number of initialized queues") which intended to fix a related
  problem, created by mentioned bug, but it's no longer necessary
- Add a new error log message if there are not enough resources to make
  XDP_TX/REDIRECT work

V1 -> V2: keep the calculation of how many tx queues can handle a single
event queue, but apply the "max. tx queues per channel" upper limit.
V2 -> V3: WARN_ON if the number of initialized XDP TXQs differs from the
expected.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>