phy: Add .set_mode and .set_speed callbacks

Add two new callbacks matching the Linux ones. The .set_mode is used to set
PHY mode and submode, where mode is either USB, Ethernet, and so on, while
submode is e.g. for Ethernet case RGMII, RMII, and so on. The .set_speed is
used to configure link speed into the PHY. Unlike the existing configure
callback, which is used to pass arbitrary custom information to the PHY,
these two callbacks are used to pass standardized set of information to
the PHY.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>