linux-postmarketos-qcom-sdm845: upgrade to 6.7.4

Changes:

• C630 support (device MR in progress).
• Some smaller patches landed upstream.

That's about it, nothing huge.

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Testing team, please try this out once CI passes! Testing instructions can be found here. Testing is done using the mrtest tool.

• Qualcomm Snapdragon 845/850 (SDM845/SDM850):
  • oneplus-enchilada (@Breakfastisready, @CarbonatedCaffeine, @Susurrus, @antonok, @crowdtier, @fdlamotte, @panzersajt, @retourmy)
  • oneplus-fajita (@Susurrus)
  • shift-axolotl (@Antoniomaciej)
  • xiaomi-beryllium (@anjandev, @panzersajt)