_projects/(imx6ull, imxrt106x): Add config for iMX ENET driver

[julianuziemblo]

Description

Provides necessary default configuration for iMX RT106x/6ULL Ethernet driver.
This PR might not be passing some tests on armv7a7-imx6ull-evk without phoenix-rtos/phoenix-rtos-lwip#96.

Motivation and Context

Part of https://jira.phoenix-rtos.com/browse/RTOS-507.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (refactoring, style fixes, git/CI config, submodule management, no code logic changes)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: armv7a7-imx6ull-evk, armv7m7-imxrt106x-evk.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order):
  • drivers/imx-enet: Add support for ethernet in imxrt1064-evk phoenix-rtos-lwip#96
• I will merge this PR by myself when appropriate.

[github-actions]

Unit Test Results

7 958 tests  ±0   7 416 ✅ ±0   40m 40s ⏱️ +30s
  470 suites ±0     542 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit effae8d. ± Comparison against base commit 81e82de.

♻️ This comment has been updated with latest results.