powerpc/mm/slb: Move comment next to the code it's referring to

There is a comment in slb_allocate() referring to the load of
paca->vmalloc_sllp, but it's several lines prior in the assembly.
We're about to change this code, and we want to add another comment,
so move the comment immediately prior to the instruction it's talking
about.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/slb_low.S

@@ -121,12 +121,13 @@ slb_miss_kernel_load_vmemmap:
 1:
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
-	/* vmalloc mapping gets the encoding from the PACA as the mapping
-	 * can be demoted from 64K -> 4K dynamically on some machines
-	 */
 	clrldi	r11,r10,48
 	cmpldi	r11,(H_VMALLOC_SIZE >> 28) - 1
 	bgt	5f
+	/*
+	 * vmalloc mapping gets the encoding from the PACA as the mapping
+	 * can be demoted from 64K -> 4K dynamically on some machines.
+	 */
 	lhz	r11,PACAVMALLOCSLLP(r13)
 	b	6f
 5: