wic: raise WicError instead of ImageError and CreatorError

There is no need to raise special exceptions. Raising
WicError should be enough.

(From OE-Core rev: b952076cc9f458c3d5eb03e12dc3ec316a44804c)

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

scripts/lib/wic/plugin.py

@@ -19,7 +19,7 @@ import os
 import sys
 import logging
 
-from wic.errors import CreatorError
+from wic.errors import WicError
 from wic import pluginbase
 from wic.utils.misc import get_bitbake_var
 
@@ -110,7 +110,7 @@ class PluginMgr():
         """ the return value is dict of name:class pairs """
 
         if ptype not in PLUGIN_TYPES:
-            raise CreatorError('%s is not valid plugin type' % ptype)
+            raise WicError('%s is not valid plugin type' % ptype)
 
         plugins_dir = self._build_plugin_dir_list(self.plugin_dir, ptype)