Don't make EEPROM size assumptions with dynamic keymaps.

[tzarc]

Description

Individuals have broken their boards by using the default assumption of having 1kB of EEPROM available.
Falling back to the transient EEPROM driver, which defaults to 36 bytes, means enabling VIA is going to attempt to obliterate up to 1kB of RAM past the start of the transient EEPROM array.

This PR fixes the dynamic keymap code such that it actually uses the selected driver's overall limit.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[sigprof]

These defines are not used in the size calculations below and may stay internal (although their values are related to FEE_ADDRESS_MAX_SIZE, because that value is determined by the encoding used here, and FEE_ADDRESS_MAX_SIZE is needed in the size checks).

[sigprof]

This also does not need to be in the header file.

[drashna]

@sigprof look good?

[sigprof]

The qmk multibuild change should be made in a separate PR, but the EEPROM changes look good (hope that they won't break existing boards — now some of them would probably get much more available space for macros).

[tzarc]

I've converted to draft while I go through and confirm binary reproducibility. As you've said, some of them have gained support for more space, I want to confirm that this is indeed the only side-effect.

[tzarc]

Looking at diff's between a handful of builds looks very much isolated to sizing changes -- traditionally more eeprom was available with the wear-leveling EEPROM-on-flash implementation but VIA was still artificially limited to 1kB by default.

[tzarc]

The qmk multibuild change should be made in a separate PR

Will raise it.