kill mm argument of vm_munmap()

it's always current->mm

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1457be3..91a5e98 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6364,7 +6364,7 @@
 	if (!user_alloc && !old.user_alloc && old.rmap && !npages) {
 		int ret;
 
-		ret = vm_munmap(current->mm, old.userspace_addr,
+		ret = vm_munmap(old.userspace_addr,
 				old.npages * PAGE_SIZE);
 		if (ret < 0)
 			printk(KERN_WARNING