geneve: use DEV_STATS_INC()

geneve updates dev->stats fields locklessly.

Adopt DEV_STATS_INC() to avoid races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240104163633.2070538-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>