samples: remove SOF sample

Sample is now maintained in the SOF repository, no need for duplication.
The SoF project maintains the board configurations and SOF related
configs better than we do.

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

MAINTAINERS.yml

@@ -2573,7 +2573,6 @@ West:
     - marc-hb
   files:
     - modules/Kconfig.sof
-    - samples/modules/sof/
   labels:
     - manifest-sof