x86: align to clflush size

Do it instead of using the conservative approach we're currently
doing. This is the way x86_64 does, and this patch makes this piece
of code the same between them, ready to be integrated.
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

include/asm-x86/dma-mapping_32.h

@@ -21,7 +21,7 @@ dma_get_cache_alignment(void)
 {
 	/* no easy way to get cache size on all x86, so return the
 	 * maximum possible, to be safe */
-	return (1 << INTERNODE_CACHE_SHIFT);
+	return boot_cpu_data.x86_clflush_size;
 }
 
 #define dma_is_consistent(d, h)	(1)