ARM: dts: s5pv210: Add missing interrupt-controller property to gph2

Adds missing interrupt-controller property to gph2 block,
to silence following warnings during build:

    /soc/pinctrl@e0200000/gph2: Missing interrupt-controller or interrupt-map property

It's reguired by Samsung Aries boards, an S5PV210 based
Samsung Galaxy S (i9000) and Galaxy S 4G phones, which are added in next patches.

Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>