gpu: ipu-v3: default to id 0 on missing OF alias

[ Upstream commit 2d87e6c1 ]

This is better than storing -ENODEV in the id number. This fixes SoCs
with only one IPU that don't specify an IPU alias in the device tree.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>