stm32/eth: Move phy_addr from Ethernet to PHY

Previously, PHY addressing was a concern of the `Ethernet` struct
which limited the `PHY` implementations which very often have to manage
multiple PHYs internally and thus possibly need to address many of them.

This change extends `StationManagement` to allow addressing different
PHY addresses via SMI.

embassy-stm32/src/eth/mod.rs

@@ -134,9 +134,9 @@ impl<'a, 'd> embassy_net_driver::TxToken for TxToken<'a, 'd> {
 /// The methods cannot move out of self
 pub unsafe trait StationManagement {
     /// Read a register over SMI.
-    fn smi_read(&mut self, reg: u8) -> u16;
+    fn smi_read(&mut self, phy_addr: u8, reg: u8) -> u16;
     /// Write a register over SMI.
-    fn smi_write(&mut self, reg: u8, val: u16);
+    fn smi_write(&mut self, phy_addr: u8, reg: u8, val: u16);
 }
 
 /// Traits for an Ethernet PHY