device: Always build device_simple.c for less code duplication

Change-Id: Iec0a11d67d7641996f26b3a01352be762006ebb6
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/26292
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/device/device.c

@@ -51,8 +51,6 @@
 #endif
 #include <timer.h>
 
-/** Linked list of ALL devices */
-struct device *all_devices = &dev_root;
 /** Pointer to the last device */
 extern struct device *last_dev;
 /** Linked list of free resources */