wic: code cleanup: wildcard imports

wic: code cleanup: wildcard imports

Here is what PEP8(Style Guide for Python Code) says about this:

Wildcard imports (from <module> import *) should be avoided, as they
make it unclear which names are present in the namespace, confusing
both readers and many automated tools.

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