Revert "samples: zms: fix dropped messages"

This reverts commit 63bb55e
which causes failures in CI on qemu_x86/atom target.

Signed-off-by: Benjamin Cabé <[email protected]>

Author: kartben

samples/subsys/fs/zms/prj.conf

@@ -3,4 +3,3 @@ CONFIG_FLASH_MAP=y
 
 CONFIG_ZMS=y
 CONFIG_LOG=y
-CONFIG_LOG_MODE_IMMEDIATE=y