riscv: dts: starfive: jh7110: Fix GMAC configuration

riscv: dts: starfive: jh7110: Fix GMAC configuration

Fixed configuration to improve the speed of TCP RX.

Before:
  # iperf3 -s
  -----------------------------------------------------------
  Server listening on 5201 (test #1)
  -----------------------------------------------------------
  Accepted connection from 192.168.1.4, port 47604
  [  5] local 192.168.1.3 port 5201 connected to 192.168.1.4 port 47612
  [ ID] Interval           Transfer     Bitrate
  [  5]   0.00-1.00   sec  36.3 MBytes   305 Mbits/sec
  [  5]   1.00-2.00   sec  35.6 MBytes   299 Mbits/sec
  [  5]   2.00-3.00   sec  36.5 MBytes   306 Mbits/sec
  [  5]   3.00-4.00   sec  36.5 MBytes   306 Mbits/sec
  [  5]   4.00-5.00   sec  35.7 MBytes   300 Mbits/sec
  [  5]   5.00-6.00   sec  35.4 MBytes   297 Mbits/sec
  [  5]   6.00-7.00   sec  37.1 MBytes   311 Mbits/sec
  [  5]   7.00-8.00   sec  35.6 MBytes   298 Mbits/sec
  [  5]   8.00-9.00   sec  36.4 MBytes   305 Mbits/sec
  [  5]   9.00-10.00  sec  36.3 MBytes   304 Mbits/sec
  - - - - - - - - - - - - - - - - - - - - - - - - -
  [ ID] Interval           Transfer     Bitrate
  [  5]   0.00-10.00  sec   361 MBytes   303 Mbits/sec        receiver

After:
  # iperf3 -s
  -----------------------------------------------------------
  Server listening on 5201 (test #1)
  -----------------------------------------------------------
  Accepted connection from 192.168.1.4, port 47710
  [  5] local 192.168.1.3 port 5201 connected to 192.168.1.4 port 47720
  [ ID] Interval           Transfer     Bitrate
  [  5]   0.00-1.00   sec   111 MBytes   932 Mbits/sec
  [  5]   1.00-2.00   sec   111 MBytes   934 Mbits/sec
  [  5]   2.00-3.00   sec   111 MBytes   934 Mbits/sec
  [  5]   3.00-4.00   sec   111 MBytes   934 Mbits/sec
  [  5]   4.00-5.00   sec   111 MBytes   934 Mbits/sec
  [  5]   5.00-6.00   sec   111 MBytes   935 Mbits/sec
  [  5]   6.00-7.00   sec   111 MBytes   934 Mbits/sec
  [  5]   7.00-8.00   sec   111 MBytes   935 Mbits/sec
  [  5]   8.00-9.00   sec   111 MBytes   934 Mbits/sec
  [  5]   9.00-10.00  sec   111 MBytes   934 Mbits/sec
  [  5]  10.00-10.00  sec   167 KBytes   933 Mbits/sec
  - - - - - - - - - - - - - - - - - - - - - - - - -
  [ ID] Interval           Transfer     Bitrate
  [  5]   0.00-10.00  sec  1.09 GBytes   934 Mbits/sec        receiver

Reviewed-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
Fixes: 1ff166c97972 ("riscv: dts: starfive: jh7110: Add ethernet device nodes")
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
[conor: converted to decimal per emil's request]
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>