powerpc/powernv: Fix endian issue in opal_xscom_read

opal_xscom_read uses a pointer to return the data so we need
to byteswap it on LE builds.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/platforms/powernv/opal-xscom.c b/arch/powerpc/platforms/powernv/opal-xscom.c
index 4d99a8f..4fbf276 100644
--- a/arch/powerpc/platforms/powernv/opal-xscom.c
+++ b/arch/powerpc/platforms/powernv/opal-xscom.c
@@ -96,9 +96,11 @@
 {
 	struct opal_scom_map *m = map;
 	int64_t rc;
+	__be64 v;
 
 	reg = opal_scom_unmangle(reg);
-	rc = opal_xscom_read(m->chip, m->addr + reg, (uint64_t *)__pa(value));
+	rc = opal_xscom_read(m->chip, m->addr + reg, (__be64 *)__pa(&v));
+	*value = be64_to_cpu(v);
 	return opal_xscom_err_xlate(rc);
 }