ARM: shmobile: r8a7740 dtsi: Remove duplicate interrupt-parent property

Caused by interaction between commit
08ec67b5 ("ARM: shmobile: r8a7740 dtsi:
Add Ethernet support") and commit 9ff254ad
("ARM: shmobile: dts: Move interrupt-parent property to root node").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>