Spelling fixes

Spelling errors found using github.com/lucasdemarchi/codespell
A tool to fix common misspellings.
This tool is licensed under GNU General Public License, version 2.

Change-Id: I78f191f26da14203dc21c97d4fc4a31f95ffc95f
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/src/pdmgen.py b/src/pdmgen.py
index 55df3e3..48d4589 100755
--- a/src/pdmgen.py
+++ b/src/pdmgen.py
@@ -144,7 +144,7 @@
 
 
 class Argument(NamedElement, Renderer):
-    '''Define argument type inteface.'''
+    '''Define argument type interface.'''
 
     def __init__(self, **kw):
         self.type = kw.pop('type', None)