powerpc: Explicit alignment for .data.cacheline_aligned

I don't think anything guarantees that the objects in data.page_aligned
are a multiple of PAGE_SIZE, thus the section may end on any boundary.

So the following section, .data.cacheline_aligned needs an explicit
alignment.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/vmlinux.lds.S

@@ -264,6 +264,7 @@ SECTIONS
 		*(.data.page_aligned)
 	}
 
+	. = ALIGN(L1_CACHE_BYTES);
 	.data.cacheline_aligned : AT(ADDR(.data.cacheline_aligned) - LOAD_OFFSET) {
 		*(.data.cacheline_aligned)
 	}