Summary

Fix two issues with the Headland chipset code:

• Fixed incorrect memory bank handling: resolves the issue where the Tandy 1000 RSX would hang on POST 03 when using 9MB of RAM
• Fixed incorrect usage of mem_set_mem_state and added remap handling for 640-1024K RAM configs: Resolves the Tandy 1000 RSX and Arche AMA-932 being unable to enable 384K remap.

Checklist

• Closes #xxx
• I have tested my changes locally and validated that the functionality works as intended
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - https://github.com/86Box/roms/pull/changeme/
• This pull request requires changes to the asset set
  • I have opened an assets pull request - https://github.com/86Box/assets/pull/changeme/

References

Provide links to datasheets or other documentation that helped you implement this pull request.

• Headland HT18 datasheet: https://theretroweb.com/chip/documentation/ht18a-b-c-64512ff1a6398435658181.pdf
• Headland HT21 datasheet: https://theretroweb.com/chip/documentation/ht21p-datasheet-64512a7179e9d102017984.pdf