um: Simplify STUB_DATA loading

As long STUB_DATA fits into 32bits we can use a plain mov.
If it will grow at some point in future we will switch to movabsq.
In any case the code is smaller and more easy to read
than the current one
Signed-off-by: NRichard Weinberger <richard@nod.at>

arch/x86/um/stub_64.S

@@ -3,10 +3,7 @@
 .section .__syscall_stub, "ax"
 	.globl batch_syscall_stub
 batch_syscall_stub:
-	mov	$(STUB_DATA >> 32), %rbx
-	sal	$32, %rbx
-	mov	$(STUB_DATA & 0xffffffff), %rax
-	or	%rax, %rbx
+	mov	$(STUB_DATA), %rbx
 	/* load pointer to first operation */
 	mov	%rbx, %rsp
 	add	$0x10, %rsp