linux-postmarketos-qcom-msm8974: upgrade to 6.7.0_rc5

Needs testing. Needs release tagging.

Tested on:

• Fairphone 2 (fairphone-fp2)
• Google Nexus 5 (lg-hammerhead) - fixed same problem as on bacon
• OnePlus One (oneplus-bacon) - seems display works during bootup but turns black once UI starts? fixed
• Samsung Galaxy Note 3 (samsung-hlte)
• Samsung Galaxy S5 (samsung-klte)
• Sony Xperia Z3 (sony-leo)