docs: networking: update XPS to account for netif_set_xps_queue

With the introduction of netif_set_xps_queue, XPS can be enabled
by the driver at initialization.

Update the documentation to reflect this, as otherwise users
may incorrectly believe that the feature is off by default.

Fixes: 537c00de ("net: Add functions netif_reset_xps_queue and netif_set_xps_queue")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/scaling.rst

@@ -465,9 +465,9 @@ XPS Configuration
 -----------------
 
 XPS is only available if the kconfig symbol CONFIG_XPS is enabled (on by
-default for SMP). The functionality remains disabled until explicitly
-configured. To enable XPS, the bitmap of CPUs/receive-queues that may
-use a transmit queue is configured using the sysfs file entry:
+default for SMP). If compiled in, it is driver dependent whether, and
+how, XPS is configured at device init. The mapping of CPUs/receive-queues
+to transmit queue can be inspected and configured using sysfs:
 
 For selection based on CPUs map::