community/soc-qcom-sdm845: fix the missing .post-install script for call audio

Currently call audio in SDM845 devices are broken in edge. I specifically wanted to address this issue in the 6.4 kernel upgrade MR and pushed an fix for it (!4201 (comment 1454159186)). But somehow it got left out in the end... Anyways let's fix it proper this time. Should partially fix call audio issue mentioned in #2237 (closed).

Tested in Oneplus 6 and Xiaomi Poco F1. Since the fix is a bit straightforward and already tested in two devices, further tests may not be necessary before merging the MR. But test from community is surely welcome!