net: ngbe: change the default ITR setting

net: ngbe: change the default ITR setting

Change the default RX/TX ITR for wx_mac_em devices from 20K to 7K, which
is an experience value from out-of-tree ngbe driver, to get higher
performance on some platforms with weak single-core performance.

TCP_SRTEAM test on Phytium 2000+ shows that the throughput of 64-Byte
packets is increased from 350.53Mbits/s to 395.92Mbits/s.

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Link: https://patch.msgid.link/20250821023408.53472-2-jiawenwu@trustnetic.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>