mm/vmalloc.c: rename VM_UNLIST to VM_UNINITIALIZED

mm/vmalloc.c: rename VM_UNLIST to VM_UNINITIALIZED

VM_UNLIST was used to indicate that the vm_struct is not listed in vmlist.
 But after commit 4341fa4 ("mm, vmalloc: remove list management of vmlist
after initializing vmalloc"), the meaning of this flag changed.  It now
means the vm_struct is not fully initialized.  So renaming it to
VM_UNINITIALIZED seems more reasonable.

Also change clear_vm_unlist to clear_vm_uninitialized_flag.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>