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

This reverts commit 606da4826b.

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>

arch/arm/mach-omap2/io.c

@@ -306,6 +306,7 @@ void __init am33xx_map_io(void)
 void __init omap4_map_io(void)
 {
 	iotable_init(omap44xx_io_desc, ARRAY_SIZE(omap44xx_io_desc));
+	omap_barriers_init();
 }
 #endif
 
@@ -313,6 +314,7 @@ void __init omap4_map_io(void)
 void __init omap5_map_io(void)
 {
 	iotable_init(omap54xx_io_desc, ARRAY_SIZE(omap54xx_io_desc));
+	omap_barriers_init();
 }
 #endif
 /*