With CONFIG_OMAP4_ERRATA_I688 enabled, omap2+ build
was broken as below:

arch/arm/kernel/io.c: In function '_memcpy_toio':
arch/arm/kernel/io.c:29: error: implicit declaration of function 'outer_sync'
make[1]: *** [arch/arm/kernel/io.o] Error 1

This was caused by commit 9f97da78 (Disintegrate asm/system.h for ARM).
Signed-off-by: NR Sricharan <r.sricharan@ti.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
[tony@atomide.com: updated comments]
Signed-off-by: NTony Lindgren <tony@atomide.com>

Disintegrate asm/system.h for ARM.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
cc: Russell King <linux@arm.linux.org.uk>
cc: linux-arm-kernel@lists.infradead.org