r8169: perform a PHY reset before any other operation at boot time

Realtek's 8139/810x (0x8136) PCI-E comes with a touchy PHY.
A big heavy reset seems to calm it down.

Fix for http://bugzilla.kernel.org/show_bug.cgi?id=7378.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: Darren Salt <linux@youmustbejoking.demon.co.uk>