olympic_open() must be __devinit

This patch fixes the following section mismatch:

<--  snip  -->

...
WARNING: drivers/net/built-in.o(.text+0x155573): Section mismatch in reference from the function olympic_open() to the function .devinit.text:olympic_init()
...

<--  snip  -->

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>