ARM: dts: Add AK8975 device node for Exynos4412 TRATS2 board

This patch adds AK8975 magnetometer node and corresponding
i2c-gpio bus node for TRATS2 board.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>