Run autoflake to remove unused imports & variables

wa/framework/target/info.py

@@ -1,5 +1,4 @@
 from devlib import AndroidTarget
-from devlib.exception import TargetError
 from devlib.target import KernelConfig, KernelVersion, Cpuinfo
 from devlib.utils.android import AndroidProperties
 

wa/framework/target/manager.py

@@ -1,5 +1,4 @@
 import logging
-import os
 
 from wa.framework import signal
 from wa.framework.plugin import Parameter

wa/framework/target/runtime_parameter_manager.py

@@ -1,4 +1,3 @@
-import re
 from collections import namedtuple
 
 from wa.framework.exception import ConfigError