powerpc: Implement a default flush_dcache_all

Implement a weak default version of flush_dcache_all which is based on
the ARM default, which is to flush the entire range via
flush_dcache_range(...).

Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/powerpc/lib/cache.c b/arch/powerpc/lib/cache.c
index e480b26..130318d 100644
--- a/arch/powerpc/lib/cache.c
+++ b/arch/powerpc/lib/cache.c
@@ -43,3 +43,12 @@
 	/* flush prefetch queue */
 	asm volatile("isync" : : : "memory");
 }
+
+/*
+ * Default implementation:
+ * do a range flush for the entire range
+ */
+void flush_dcache_all(void)
+{
+	flush_dcache_range(0, ~0);
+}