ARC: Revert "ARC: mm: IOC: Don't enable IOC by default"

The programming model has been fixed with prev patches so re-enable it
by default

This reverts commit 23cb1f64.
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>

arch/arc/mm/cache.c

@@ -23,7 +23,7 @@
 
 static int l2_line_sz;
 static int ioc_exists;
-int slc_enable = 1, ioc_enable = 0;
+int slc_enable = 1, ioc_enable = 1;
 unsigned long perip_base = ARC_UNCACHED_ADDR_SPACE; /* legacy value for boot */
 unsigned long perip_end = 0xFFFFFFFF; /* legacy value */