staging: lustre: Use is_vmalloc_addr

Instead of manually checking the bounds of VMALLOC_START and
VMALLOC_END, just use is_vmalloc_addr. That's what the function
was designed for.
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c

@@ -529,8 +529,7 @@ kiblnd_kvaddr_to_page (unsigned long vaddr)
 {
 	struct page *page;
 
-	if (vaddr >= VMALLOC_START &&
-	    vaddr < VMALLOC_END) {
+	if (is_vmalloc_addr(vaddr)) {
 		page = vmalloc_to_page ((void *)vaddr);
 		LASSERT (page != NULL);
 		return page;