net/udp: fix udp message cannot be sent to the network card

[HedongGao]

Summary

To fix the issue 17758
Udp message cannt be sent to the network card

Impact

It only fixes the issue and will not affect the api, function and performance.

Testing

Build the sim: userfs environment, and verify that issue 17758 can be fixed.
Set up the sim: matter environment, enable CONFIG_EXAMPLES_UDP, modify udp_client. c, and send data with udp_len greater than or equal to 0 at the same time. The results show that both types of data can be sent to the host side.

[xiaoxiang781216]

@HedongGao fix:

../nuttx/tools/checkpatch.sh -c -u -m -g f53b986fb2042b5090fe29f8516243b67aafc6e1..HEAD
❌ Missing git commit message
Used config files:
    1: .codespellrc
Some checks failed. For contributing guidelines, see:
  https://github.com/apache/nuttx/blob/master/CONTRIBUTING.md
Error: Process completed with exit code 1.

[HedongGao]

@HedongGao fix:

../nuttx/tools/checkpatch.sh -c -u -m -g f53b986fb2042b5090fe29f8516243b67aafc6e1..HEAD
❌ Missing git commit message
Used config files:
    1: .codespellrc
Some checks failed. For contributing guidelines, see:
  https://github.com/apache/nuttx/blob/master/CONTRIBUTING.md
Error: Process completed with exit code 1.

DONE!