powerpc/wii: properly disable use of BATs when requested.

BugLink: https://bugs.launchpad.net/bugs/1822271

commit 6d183ca8 upstream.

'nobats' kernel parameter or some options like CONFIG_DEBUG_PAGEALLOC
deny the use of BATS for mapping memory.

This patch makes sure that the specific wii RAM mapping function
takes it into account as well.

Fixes: de32400d ("wii: use both mem1 and mem2 as ram")
Cc: stable@vger.kernel.org
Reviewed-by: Jonathan Neuschafer <j.neuschaefer@gmx.net>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/platforms/embedded6xx/wii.c

@@ -104,6 +104,10 @@ unsigned long __init wii_mmu_mapin_mem2(unsigned long top)
 	/* MEM2 64MB@0x10000000 */
 	delta = wii_hole_start + wii_hole_size;
 	size = top - delta;
+
+	if (__map_without_bats)
+		return delta;
+
 	for (bl = 128<<10; bl < max_size; bl <<= 1) {
 		if (bl * 2 > size)
 			break;