Fix PatchApplier init order (#1762)

#### What I did
Otherwise PatchSorter will see both config_wrapper, patch_wrapper as None.

#### How I did it

#### How to verify it

#### Previous command output (if the output of a command-line utility has changed)

#### New command output (if the output of a command-line utility has changed)

Author: qiluo-msft

generic_config_updater/generic_updater.py

@@ -32,10 +32,10 @@ def __init__(self,
                  changeapplier=None,
                  config_wrapper=None,
                  patch_wrapper=None):
-        self.patchsorter = patchsorter if patchsorter is not None else PatchSorter(config_wrapper, patch_wrapper)
-        self.changeapplier = changeapplier if changeapplier is not None else ChangeApplier()
         self.config_wrapper = config_wrapper if config_wrapper is not None else ConfigWrapper()
         self.patch_wrapper = patch_wrapper if patch_wrapper is not None else PatchWrapper()
+        self.patchsorter = patchsorter if patchsorter is not None else PatchSorter(self.config_wrapper, self.patch_wrapper)
+        self.changeapplier = changeapplier if changeapplier is not None else ChangeApplier()
 
     def apply(self, patch):
         # validate patch is only updating tables with yang models