geneve: Handle stats using NETDEV_PCPU_STAT_DSTATS.

Geneve uses the TSTATS infrastructure (dev_sw_netstats_*()) for RX
packet counters. All other counters are handled using atomic increments
with DEV_STATS_INC().

Let's convert packet stats handling to DSTATS, which has a per-cpu
counter for packet drops too, to avoid the cost of atomic increments
in these cases. Statistics that don't fit DSTATS are still updated
atomically with DEV_STATS_INC().

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/7af5c09f3c26f0f231fbe383822ca5d1ce0278fa.1733313925.git.gnault@redhat.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>