Add the missing fifth interrupt to the device node that represents the
ARM architected timer.  While at it, add an interrupt-names property for
clarity,

Fixes: cf40c968 ("arm64: dts: renesas: Add initial DTSI for RZ/G2UL SoC")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/15cc7a7522b1658327a2bd0c4990d0131bbcb4d7.1718890849.git.geert+renesas@glider.be