Merge branch 'netdevsim-implement-rx-statistics-using-netdev_pcpu_stat_dstats'

Merge branch 'netdevsim-implement-rx-statistics-using-netdev_pcpu_stat_dstats'

Breno Leitao says:

====================
netdevsim: implement RX statistics using NETDEV_PCPU_STAT_DSTATS

The netdevsim driver previously lacked RX statistics support, which
prevented its use with the GenerateTraffic() test framework, as this
framework verifies traffic flow by checking RX byte counts.

This patch migrates netdevsim from its custom statistics collection to
the NETDEV_PCPU_STAT_DSTATS framework, as suggested by Jakub. This
change not only standardizes the statistics handling but also adds the
necessary RX statistics support required by the test framework.

v3: https://lore.kernel.org/20250617-netdevsim_stat-v3-0-afe4bdcbf237@debian.org
v2: https://lore.kernel.org/20250613-netdevsim_stat-v2-0-98fa38836c48@debian.org
v1: https://lore.kernel.org/20250611-netdevsim_stat-v1-0-c11b657d96bf@debian.org
====================

Link: https://patch.msgid.link/20250618-netdevsim_stat-v4-0-19fe0d35e28e@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>