Add kernel args boot volume "packaged" flag

* Add BOOT_VOLUME_PACKAGED boot volume message field name constant.
* register_boot_file_system():
  - Now takes a BootVolume& parameter.
  - If the boot volume is packaged, add that info to the boot volume
    message.

headers/private/kernel/boot/kernel_args.h

@@ -27,6 +27,7 @@
 #define BOOT_METHOD						"boot method"
 #define BOOT_VOLUME_USER_SELECTED		"user selected"
 #define BOOT_VOLUME_BOOTED_FROM_IMAGE	"booted from image"
+#define BOOT_VOLUME_PACKAGED			"packaged"
 #define BOOT_VOLUME_PARTITION_OFFSET	"partition offset"
 #define BOOT_VOLUME_DISK_IDENTIFIER		"disk identifier"
 

headers/private/kernel/boot/vfs.h

@@ -136,7 +136,7 @@ private:
 /* function prototypes */
 
 extern status_t vfs_init(stage2_args *args);
-extern status_t register_boot_file_system(Directory *directory);
+extern status_t register_boot_file_system(BootVolume& bootVolume);
 extern status_t get_boot_file_system(stage2_args* args,
 			BootVolume& _bootVolume);
 extern status_t mount_file_systems(stage2_args *args);