net: bcmgenet: fix bcmgenet_wol_resume

bcmgenet_wol_resume() will create an unbalanced clock state for the
wol_clk clock pointer since everywhere else in the code, we always call
clk_prepare_enable() and clk_disable_unprepare(). This function also
calls init_umac() which is neither correct nor necessary since
bcmgenet_resume() and bcmgenet_open() already does that.

Finally calling bcmgenet_wol_resume() in bcmgenet_open() is not correct,
since the interface would not have been able to put us in Wake-on-LAN
mode if it was not UP before.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>