sh_eth: propagate platform_get_irq() error upstream

The driver overrides the error returned by platform_get_irq() with -ENODEV
which e.g. precludes the deferred  probing from working. Propagate the real
error code to the driver core instead.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: David S. Miller <davem@davemloft.net>