west.yml: update zephyr to 8c6b2c8c887

Total of 1263 commits.

Changes include:

* fbafada9b64 soc: intel_adsp: Manage power gating based on core
              activity
* 5a9394a1e07 llext:  add dynamic heap allocation support
* 3aace9520f1 llext: Do not print symbol resolution messages
* a8d44c37c49 pm: policy: remove redundant ifdef exclusion of
              device_power_lock
* b6429254914 pm: policy: fix mocks of
              CONFIG_PM_POLICY_DEVICE_CONSTRAINTS
* 437b56d22e8 pm: device_runtime: Make async optional
* 64e38bab556 pm: device_runtime: Allow to use a dedicated wq
* 1b230f87411 pm: policy: default: Removed unused code
* 042bf2c3fae kernel: userspace: Fix memory leak in
              dynamic_object_create
* 240b56008ce drivers: ssp: unify clock selection flow across ACE
              platforms

Signed-off-by: Tomasz Leman <tomasz.m.leman@intel.com>

Author: tmleman

west.yml

@@ -43,7 +43,7 @@ manifest:
 
     - name: zephyr
       repo-path: zephyr
-      revision: e48c90700de7b84c038e73d01f4b2640e2fea127
+      revision: 8c6b2c8c88773810d64a47ed3b6206b7d6e8290f
       remote: zephyrproject
 
       # Import some projects listed in zephyr/west.yml@revision