arm: Support cache invalidate

At present there is not operation to invalidate a cache range. This seems
to be needed to fill out the cache operations. Add an implementation based
on the flush operation.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c
index bd1c3e0..adc7e17 100644
--- a/arch/arm/cpu/armv8/cache_v8.c
+++ b/arch/arm/cpu/armv8/cache_v8.c
@@ -446,7 +446,7 @@
  */
 void invalidate_dcache_range(unsigned long start, unsigned long stop)
 {
-	__asm_flush_dcache_range(start, stop);
+	__asm_invalidate_dcache_range(start, stop);
 }
 
 /*