ARM: davinci: da850: move interrupt-parent property to soc node

This patch moves 'interrupt-parent' property to soc node, so that
the child inherits this property. This avoids adding 'interrupt-parent'
property to each node.

Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: davinci-linux-open-source@linux.davincidsp.com
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Heiko Schocher <hs@denx.de>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>