west: Fix unused import and variable

Making a clean slate for a pylint test in CI.

'_' is a common name for non-problematic unused variables in Python.
pylint knows not to flag it.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
diff --git a/scripts/west_commands/zcmake.py b/scripts/west_commands/zcmake.py
index ecd8aac..85e0b8d 100644
--- a/scripts/west_commands/zcmake.py
+++ b/scripts/west_commands/zcmake.py
@@ -57,7 +57,7 @@
 
     log.dbg('Running CMake:', quote_sh_list(cmd), level=log.VERBOSE_NORMAL)
     p = subprocess.Popen(cmd, **kwargs)
-    out, err = p.communicate()
+    out, _ = p.communicate()
     if p.returncode == 0:
         if out:
             return out.decode(sys.getdefaultencoding()).splitlines()