eth: nfp: Remove u64_stats_update_begin()/end() for stats fetch

This place is fetching the stats, u64_stats_update_begin()/end()
should not be used, and the fetcher of stats is in the same
context as the updater of the stats, so don't need any protection

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20250815015619.2713-1-lirongqing@baidu.com


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