ARM: EXYNOS: remove unused <mach/memory.h>

ARCH_EXYNOS doesn't select NEED_MACH_MEMORY_H, so <asm/memory.h> doesn't
include <mach/memory.h> and so this file is not used and can go away.

Signed-off-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
[t.figa@samsung.com: boot tested on Exynos4412-based Trats2 board]
Tested-by: Tomasz Figa <t.figa@samsung.com>
Reviewed-by: Sachin Kamat <sachin.kamat@samsung.com>
[sachin.kamat: Tested on Arndale octa board (Exynos 5420)]
Tested-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>