net: phy: leds: Break dependency of phy.h on phy_led_triggers.h

<linux/phy.h> includes <linux/phy_led_triggers.h>, which is not really
needed.  Drop the include from <linux/phy.h>, and add it to all users
that didn't include it explicitly.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>