net: dsa: realtek: rtl8365mb: remove ifOutDiscards from rx_packets

rx_packets should report the number of frames successfully received:
unicast + multicast + broadcast. Subtracting ifOutDiscards (a TX
counter) is incorrect and can undercount RX packets. RX drops are
already reported via rx_dropped (e.g. etherStatsDropEvents), so
there is no need to adjust rx_packets.

This patch removes the subtraction of ifOutDiscards from rx_packets
in rtl8365mb_stats_update().

Link: https://lore.kernel.org/netdev/878777925.105015.1763423928520@mail.yahoo.com/
Fixes: 4af2950c50c8 ("net: dsa: realtek-smi: add rtl8365mb subdriver for RTL8365MB-VC")
Signed-off-by: Mieczyslaw Nalewaj <namiltd@yahoo.com>
Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260303-realtek_namiltd_fix2-v1-1-bfa433d3401e@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>