input: un-constify dev->name

Fallout from fecc7eb1cf, and reverts most of the
rest of that patch.

The device name is allocated and may even change during PreInit. The const
warnings came from the test codes, the correct fix here is to fix the test
code.

touch.c: In function ‘touch_init’:
touch.c:254:14: warning: assignment discards ‘const’ qualifier from pointer target type [enabled by default]
     dev.name = "test device";

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

include/inputstr.h

@@ -542,7 +542,7 @@ typedef struct _DeviceIntRec {
     GrabInfoRec deviceGrab;     /* grab on the device */
     int type;                   /* MASTER_POINTER, MASTER_KEYBOARD, SLAVE */
     Atom xinput_type;
-    const char *name;
+    char *name;
     int id;
     KeyClassPtr key;
     ValuatorClassPtr valuator;