arm: cache: Drop a stale comment

This header includes more than just dummy functions, so drop this
comment.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/lib/cache.c b/arch/arm/lib/cache.c
index b2ae74a..648edf3 100644
--- a/arch/arm/lib/cache.c
+++ b/arch/arm/lib/cache.c
@@ -4,8 +4,6 @@
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  */
 
-/* for now: just dummy functions to satisfy the linker */
-
 #include <config.h>
 #include <cpu_func.h>
 #include <log.h>