powerpc: Add the old invalidate_icache_all function

Add the old invalidate_icache_all function that prints a warning that
was previously found in cmd/cache.c

Signed-off-by: Tom Rini <trini@konsulko.com>

arch/powerpc/lib/cache.c

@@ -5,6 +5,7 @@
  */
 
 #include <cpu_func.h>
+#include <stdio.h>
 #include <asm/cache.h>
 #include <watchdog.h>
 
@@ -52,3 +53,8 @@ void flush_dcache_all(void)
 {
 	flush_dcache_range(0, ~0);
 }
+
+void invalidate_icache_all(void)
+{
+	puts("No arch specific invalidate_icache_all available!\n");
+}