net: phy: microchip_t1: add lan87xx_config_rgmii_delay for lan87xx phy

Add a function to initialize phy rgmii delay according to phydev->interface.

Signed-off-by: Yuiko Oshino <yuiko.oshino@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20211101162119.29275-1-yuiko.oshino@microchip.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>