net: stmmac: stm32: use PHY_INTF_SEL_x to select PHY interface

net: stmmac: stm32: use PHY_INTF_SEL_x to select PHY interface

Convert dwmac-stm32 to use the PHY_INTF_SEL_x definitions.

For stm32mp1, the original definitions used constant 0 (GMII, 0 << 21),
BIT(21) (RGMII, 1 << 21) and BIT(23) (RMII, 4 << 21) to define these,
but from the values it can be clearly seen that these are the
PHY_INTF_SEL_x inputs to the dwmac.

For stm32mp2, the original definitions cover a bitfield 6:4 in the
SYSCFG Ethernet1 control register (according to documentation) and use
the PHY_INTF_SEL_x values.

Use the common dwmac definitions for the PHY interface selection field
by adding the bitfield mask, and using FIELD_PREP() for the bitfield
values.

This removes this incorrect use of BIT().

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1vIjUK-0000000Dqtn-1AyK@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>