ARM: dts: Add PPMU node for exynos4412-trats2

This patch add dt node for PPMU_{DMC0|DMC1|LEFTBUS|RIGHTBUS} for
exynos4412-trats2 board. Each PPMU dt node includes one event of
'PPMU Count3'.

Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>