Typo writting BPF (#659)

src/python/bcc/__init__.py

@@ -482,7 +482,7 @@ class BPF(object):
         if res < 0:
             err_no = ct.get_errno()
             if err_no == errno.EBADMSG:
-                raise Exception("Internal error while attaching BFP to device,"+
+                raise Exception("Internal error while attaching BPF to device,"+
                     " try increasing the debug level!")
             else:
                 errstr = os.strerror(err_no)