powerpc/mm: Fix handling of _PAGE_COHERENT in BAT setup code

_PAGE_COHERENT is now always set in _PAGE_RAM resp. PAGE_KERNEL.
Thus it has to be masked out, if the BAT mapping should be non
cacheable or CPU_FTR_NEED_COHERENT is not set.

This will work on normal SMP setups because we force-set
CPU_FTR_NEED_COHERENT as part of CPU_FTR_COMMON on SMP.
Signed-off-by: Gerhard Pircher <gerhard_pircher@gmx.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/mm/ppc_mmu_32.c

@@ -123,9 +123,9 @@ void __init setbat(int index, unsigned long virt, phys_addr_t phys,
 	int wimgxpp;
 	struct ppc_bat *bat = BATS[index];
 
-	if (((flags & _PAGE_NO_CACHE) == 0) &&
-	    cpu_has_feature(CPU_FTR_NEED_COHERENT))
-		flags |= _PAGE_COHERENT;
+	if ((flags & _PAGE_NO_CACHE) ||
+	    (cpu_has_feature(CPU_FTR_NEED_COHERENT) == 0))
+		flags &= ~_PAGE_COHERENT;
 
 	bl = (size >> 17) - 1;
 	if (PVR_VER(mfspr(SPRN_PVR)) != 1) {