net: gemini: Fix copy/paste error

The TX stats should be started with the tx_stats_syncp,
there seems to be a copy/paste error in the driver.

Signed-off-by: Andreas Fiedler <andreas.fiedler@gmx.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>