linux-postmarketos-qcom-msm8953: upgrade to 6.6.8-r0

Relevant kconfig changes:

• QCOM_PBS=m
• CONFIG_NVMEM_SPMI_SDAM=m
• CONFIG_QCOM_CLK_APCS_MSM8953=y

Kernel changes:

• Upgrade to 6.6.8
• Add PBS client and use in LPG node
• xiaomi-daisy: add goodix gt917d touchscreen
• Fix digital audio codec mbhc-vthreshold values

and many other fixes

Tested community devices:

• xiaomi-daisy
• xiaomi-markw
• xiaomi-mido
• xiaomi-tissot
• xiaomi-vince
• xiaomi-ysl

Tested non-community devices:

• fairphone-fp3
• motorola-ali
• motorola-ocean
• motorola-potter
• samsung-a6plte
• xiaomi-onclite