of/irq: Fix of_irq_parse_one() returned error codes

The error code paths that require cleanup use a goto to jump to the
cleanup code and return an error code. However, the error code variable
res, which is initialized to -EINVAL when declared, is then overwritten
with the return value of of_parse_phandle_with_args(), and reused as the
return code from of_irq_parse_one(). This leads to an undetermined error
being returned instead of the expected -EINVAL value. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: stable@vger.kernel.org # 3.13+
Signed-off-by: Rob Herring <robh@kernel.org>