soc/tegra: Don't leak device tree node reference

[ Upstream commit 9eb40fa2cd2d1f6829e7b49bb22692f754b9cfe0 ]

of_find_node_by_path() acquires a reference to the node returned by it
and that reference needs to be dropped by its caller. soc_is_tegra()
doesn't do that, so fix it.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
[treding: slightly rewrite to avoid inline comparison]
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>