net: phy: implements probe for Cortina phy

Cortina phy cannot support soft reset, this commit implements probe
for Cortina PHY to tell phylib to skip phy soft reset by setting
PHY_FLAG_BROKEN_RESET in flags.

Signed-off-by: Shaohui Xie <Shaohui.Xie@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>