Switch from FLAGS to CONF in misc modules

Use the global CONF variable instead of FLAGS. This is purely a cleanup
since FLAGS is already just another reference to CONF.

We leave the nova.flags imports until a later cleanup commit since
removing them may cause unpredictable problems due to config options not
being registered.

Change-Id: Ib110ba8d1837780e90b0d3fe13f8e6b68ed15f65

nova/block_device.py

@@ -17,9 +17,10 @@
 
 import re
 
+from nova import config
 from nova import flags
 
-FLAGS = flags.FLAGS
+CONF = config.CONF
 
 DEFAULT_ROOT_DEV_NAME = '/dev/sda1'
 _DEFAULT_MAPPINGS = {'ami': 'sda1',
@@ -94,7 +95,7 @@ def instance_block_mapping(instance, bdms):
     root_device_name = instance['root_device_name']
     # NOTE(clayg): remove this when xenapi is setting default_root_device
     if root_device_name is None:
-        if FLAGS.compute_driver.endswith('xenapi.XenAPIDriver'):
+        if CONF.compute_driver.endswith('xenapi.XenAPIDriver'):
             root_device_name = '/dev/xvda'
         else:
             return _DEFAULT_MAPPINGS