enable current kernel for hinlink-h6xk boards

[amazingfate]

Description

When toggling kernel from vendor to mainline in #7559 the current branch of rockchip64 is not bumped to 6.12, now we can enable both current and edge.

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• not tested, which should just work

Checklist:

Please delete options that are not relevant.

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[igorpecovnik]

Perhaps also add KERNEL_TEST_TARGET=current to limit making test images to CURRENT.