Revert "app/prj.conf: restore CONFIG_CLEANUP_INTERMEDIATE_FILES=n def…

…ault"

This reverts commit 80c6738.

The Zephyr default changed in commit 385ad46a39ca so this is not needed
anymore.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

app/prj.conf

@@ -9,14 +9,6 @@ CONFIG_BUILD_OUTPUT_BIN=n
 # and usage in xtensa-build-zephyr.py
 CONFIG_BUILD_OUTPUT_STRIPPED=y
 
-# Zephyr has hardcoded this to 'y' because it saves CI some disk space
-# when compiling hundreds of different zephyr/tests/, each in a separate
-# build directory. But when compiling just one "sof/app" it saves
-# practically no space, breaks the incremental build and can make it
-# more difficult to troubleshoot some build issues. So, reset it to the
-# default value.
-CONFIG_CLEANUP_INTERMEDIATE_FILES=n
-
 # Generate zephyr.lst file
 CONFIG_OUTPUT_DISASSEMBLY=y