phy: ti: gmii-sel: add resume support

The resume callback restores the submode of each PHY.

It uses the submode stored in struct phy_gmii_sel_phy_priv (variable
phy_if_mode). The submode was saved by the set_mode PHY operation.

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/20240125171754.773909-1-thomas.richard@bootlin.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>