net: phylink: rename 'ops' to 'mac_ops'

Rename the bland 'ops' member of struct phylink to be a more
descriptive 'mac_ops' - this is necessary as we're about to introduce
another set of operations.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>