Consolidated and fixed device_geometry computation.

* The only implementation that would accept more than 2 TB was the one in
  scsi_disk. But even that one was limited to 63 TB.
* Now there is a new utility function devfs_compute_geometry_size() which
  does it correctly for sizes up to 2^64 which should be good enough for
  quite some time :-)
* This fixes bug #8992.

headers/private/kernel/fs/devfs.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008, Axel Dörfler, [email protected]. All rights reserved.
+ * Copyright 2002-2012, Axel Dörfler, [email protected].
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
@@ -29,6 +29,9 @@ status_t devfs_publish_device(const char *path, device_hooks *calls);
 status_t devfs_publish_directory(const char *path);
 status_t devfs_rescan_driver(const char *driverName);
 
+void devfs_compute_geometry_size(device_geometry* geometry, uint64 blockCount,
+	uint32 blockSize);
+
 #ifdef __cplusplus
 }
 #endif