PCI: tegra: Fix OF node reference leak

Each iteration of for_each_child_of_node() executes of_node_put() on the
previous node, but in some return paths in the middle of the loop
of_node_put() is missing thus causing a reference leak.

Hence stash these mid-loop return values in a variable 'err' and add a
new label err_node_put which executes of_node_put() on the previous node
and returns 'err' on failure.

Change mid-loop return statements to point to jump to this label to
fix the reference leak.

Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
[lorenzo.pieralisi@arm.com: rewrote commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>