[coreboot] [coreboot - Refactoring #460] Make mainboards using the variant concept

[Nico Huber]

Issue #460 has been updated by Nico Huber.

I mean `lga1155` and `lga1150` respectively.

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Refactoring #460: Make mainboards using the variant concept
https://ticket.coreboot.org/issues/460#change-1417

* Author: Felix Singer
* Status: New
* Priority: Normal
* Target version: none
* Start date: 2023-02-14
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* asrock/ivybridge
  * asrock/b75pro3-m
  * asrock/h77pro4-m

* asrock/haswell
  * asrock/b85m_pro4
  * asrock/h81m-hds