net: ftgmac100: Enable TX interrupt to avoid TX timeout

net: ftgmac100: Enable TX interrupt to avoid TX timeout

Currently, the driver only enables RX interrupt to handle RX
packets and TX resources. Sometimes there is not RX traffic,
so the TX resource needs to wait for RX interrupt to free.
This situation will toggle the TX timeout watchdog when the MAC
TX ring has no more resources to transmit packets.
Therefore, enable TX interrupt to release TX resources at any time.

When I am verifying iperf3 over UDP, the network hangs.
Like the log below.

root# iperf3 -c 192.168.100.100 -i1 -t10 -u -b0
Connecting to host 192.168.100.100, port 5201
[  4] local 192.168.100.101 port 35773 connected to 192.168.100.100 port 5201
[ ID] Interval           Transfer     Bandwidth       Total Datagrams
[  4]   0.00-20.42  sec   160 KBytes  64.2 Kbits/sec  20
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
[  4]  20.42-20.42  sec  0.00 Bytes  0.00 bits/sec  0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval          Transfer    Bandwidth      Jitter   Lost/Total Datagrams
[  4]   0.00-20.42  sec  160 KBytes 64.2 Kbits/sec 0.000 ms 0/20 (0%)
[  4] Sent 20 datagrams
iperf3: error - the server has terminated

The network topology is FTGMAC connects directly to a PC.
UDP does not need to wait for ACK, unlike TCP.
Therefore, FTGMAC needs to enable TX interrupt to release TX resources instead
of waiting for the RX interrupt.

Fixes: 10cbd6407609 ("ftgmac100: Rework NAPI & interrupts handling")
Signed-off-by: Jacky Chou <jacky_chou@aspeedtech.com>
Link: https://patch.msgid.link/20240906062831.2243399-1-jacky_chou@aspeedtech.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>