Fix #3, change HK_INPUTMID_SUBSCRIBED to 1

[havencarlson]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
Fix #3, change macro HK_INPUTMID_SUBSCRIBED from 0xFF to 1

Testing performed
Unit testing

Expected behavior changes
No impact to behavior

System(s) tested on

• OS: Ubuntu 18.04

Contributor Info - All information REQUIRED for consideration of pull request
Haven Carlson - NASA

[skliper]

Recommend closing, original issue lacks justification. Why change just the value? If it was true/false the unique defines could go away which would make more sense to me... but just a value change doesn't simplify anything.