ARM: dts: Split memory into 4 sections for exynos4210-trats

Since the maximum section size on mach-exynos is set to 256MiB, boards
with memory configuration defined using sections bigger than 256MiB will
fail to boot with a kernel panic.

This patch modifies the dts file of Samsung Trats board to define four
sections of 256MiB instead of two of 512MiB to fix the boot problem.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>