Revert "ARM: OMAP4: remove dead kconfig option OMAP4_ERRATA_I688"

This reverts commit 606da4826b89b044b51e3a84958b802204cfe4c7.

We actually need this code for proper behaviour of OMAP4, and it needs
fixing a different way other than just removing the code.  Disabling
code which is necessary in the hopes of persuing multiplatform kernels
is a stupid approach.

Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-omap2/common.c b/arch/arm/mach-omap2/common.c
index eae6a0e..484cdad 100644
--- a/arch/arm/mach-omap2/common.c
+++ b/arch/arm/mach-omap2/common.c
@@ -30,4 +30,5 @@
 void __init omap_reserve(void)
 {
 	omap_secure_ram_reserve_memblock();
+	omap_barrier_reserve_memblock();
 }