Increase retries times on ObjectPathInUse exception

In get_object_async() when calling ObjectMapper.GetObject(),
ObjectPathInUse exception may raise and it will retry.
Previously it retries for 5 times with 1000ms interval, it sometimes
cause get_object_async() raise this exception and system_manager
will not enter BMC_READY state.

This workaround increases the retry times to 20 and reduce the
interval to 500ms, so far the issue is not reproduced.

Partially fix openbmc/openbmc#862

Change-Id: Icaccc31c896e52b1c056007dff5c72d213bb7fa8
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/obmc/mapper/utils.py b/obmc/mapper/utils.py
index 6dd3750..d7075bd 100644
--- a/obmc/mapper/utils.py
+++ b/obmc/mapper/utils.py
@@ -34,9 +34,9 @@
         self.done = False
         self.callback = kw.pop('callback', None)
         self.error_callback = kw.pop('error_callback', self.default_error)
-        self.busy_retries = kw.pop('busy_retries', 5)
+        self.busy_retries = kw.pop('busy_retries', 20)
         self.busy_retry_delay_milliseconds = kw.pop(
-            'busy_retry_delay_milliseconds', 1000)
+            'busy_retry_delay_milliseconds', 500)
         self.waitlist_keyword = kw.pop('waitlist_keyword', None)
 
         self.bus.add_signal_receiver(