system/readline: Fix small issues

[acassis]

Summary

This PR fixes some small issues raised by Xiang Xiao.

Impact

Improvement

Testing

Tested on nsh_readline_test_suite.py

##############################################################################
# RESULTS: 582/583 passed, 0 failed, 1 known limitation(s)
# (3 of the passes needed an isolated re-run to confirm -- see notes above; this is simulator I/O-scheduling flakiness under sustained load, not a readline defect)
##############################################################################
``

[acassis]

@xiaoxiang781216 maybe we could include this test suite in our CI (or ideally modify it to be included into NTFC)
nsh_readline_test_suite.py

[cederom]

Thank you @acassis and @xiaoxiang781216 :-)

[cederom]

Argh sorry @xiaoxiang781216 I have re-requested review and that cleared your approval my apologies o_O

[cederom]

@acassis: @xiaoxiang781216 maybe we could include this test suite in our CI (or ideally modify it to be included into NTFC) nsh_readline_test_suite.py

@raiden00pl :-)

[acassis]

Disabled the Lined Editing to TIVA Board : QEMU Protected because the board reports there is no free space:

apache/nuttx#19546

Building locally it says there are more than 60KB of free space.

[raiden00pl]

@acassis you can extend https://github.com/apache/nuttx-ntfc-testing/tree/main/arch/nsh but you need port these tests to ntfc/pytest format. This is a good idea, it's worth creating an issue about it