west.yml: update zephyr to 9852e8e15bc8

[kv2019i]

Total of 287 commits with no known impact to SOF to builds.

[kv2019i]

The larger updates (to newer Zephyr) have failed so badly this month (#8796 , #8764 and #8747), so let's try a smaller update first.

[kv2019i]

Pretty good results (as expected). There's one fail in https://sof-ci.01.org/sofpr/PR8797/build2328/devicetest/index.html?model=MTLP_RVP_NOCODEC&testcase=multiple-pipeline-playback that is unexpected. No errors in kernel or mtrace logs, but data does not start moving to the SSP1/PCM1, so aplay times out. Given we need to wait for tomorrow for reviews, let me re-kick the SOF CI to get more data.

[kv2019i]

SOFCI TEST

[marc-hb]

SOFCI TEST

You just lost the URLs to the previous runs :-(

[kv2019i]

Test results now look ok, one system-PM fail in https://sof-ci.01.org/sofpr/PR8797/build2334/devicetest/index.html but this is a known thing. I'll proceed to merge this smaller increment and we can continue to take a bite of the more controversial Zephyr upstream changes in next.