zdev: add site specific states for devices

Currently zdev supports the configuration and maintenance of one single
persistent device state. With the introduction of sites, zdev should be
able to store, configure and maintaine NUM_SITES number of states in
the persistent configuration. This patch modifies the struct device and
adds a new site_specific device_state array, which stores the
persistent configuration for all the available sites.

Total number of available sites are configured with NUM_SITES. Where,
10 site-specific configurations and 1 common configuration.

1. during read, all site data is always read and update the
   site_specific[] array.
2. dev->persistent is a copy of dev->site_specific[global_site_id]
3. modifications are only done on dev->persistent, and during write
   dev->persistent overlays dev->site_specific[global_site_id]

Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/include/device.h

@@ -75,6 +75,7 @@ struct device {
 	struct device_state active;
 	struct device_state persistent;
 	struct device_state autoconf;
+	struct device_state site_specific[NUM_SITES];
 
 	unsigned int processed:1;
 };