myri10ge: Fix an error handling path in myri10ge_probe()

Some memory allocated in myri10ge_probe_slices() is not released in the
error handling path of myri10ge_probe().

Add the corresponding kfree(), as already done in the remove function.

Fixes: 0dcffac1 ("myri10ge: add multislices support")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>