arm64: dts: renesas: r8a77990: Fix VIN endpoint numbering

The VIN driver bindings dictates fixed numbering for VIN endpoints connected
to CSI-2 endpoints, even when a single endpoint exists.

Without proper endpoint numbering the VIN driver fails to probe.

Based on a patch in BSP from Koji Matsuoka <koji.matsuoka.xm@renesas.com>

Fixes: ec70407a ("arm64: dts: renesas: r8a77990: Add VIN and CSI-2 device nodes")
Signed-off-by: Koji Matsuoka <koji.matsuoka.xm@renesas.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>