wic: Code cleanup: unused imports

Fixed pylint warning unused-import

(From OE-Core rev: e77fda5fb6cb0a35308e4620ca4602715a471fbe)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/plugins/source/bootimg-efi.py

@@ -27,7 +27,6 @@
 import os
 import shutil
 
-from wic.utils.errors import ImageError
 from wic import kickstart, msger
 from wic.pluginbase import SourcePlugin
 from wic.utils.oe.misc import exec_cmd, exec_native_cmd, get_bitbake_var, \