stm32/eth: Code cleanup - remove unused constant and fix issues.

This commit addresses 4 issues found during comprehensive code review:

1. Remove unused MAC_RECONFIG_DELAY_MS constant (all uses were removed
   when fixed delays were replaced with descriptor polling).

2. Initialize mac_speed_configured and autoneg_start_ms in eth_init()
   to prevent uninitialized values between eth_init() and eth_start().

3. Fix misleading comment about DHCP restart - the link-down handler
   only does dhcp_stop(), not dhcp_start().

4. Remove extra blank line in eth_phy.h.

No functional changes, purely cleanup.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

ports/stm32/eth.c

@@ -203,6 +203,8 @@ int eth_init(eth_t *self, int mac_idx, uint32_t phy_addr, int phy_type) {
     self->last_link_status = false;
     self->enabled = false;
     self->mac_reconfig_in_progress = false;
+    self->mac_speed_configured = false;
+    self->autoneg_start_ms = 0;
     if (phy_type == ETH_PHY_DP83825 || phy_type == ETH_PHY_DP83848) {
         self->phy_get_link_status = eth_phy_dp838xx_get_link_status;
     } else if (phy_type == ETH_PHY_LAN8720 || phy_type == ETH_PHY_LAN8742) {

ports/stm32/eth_phy.h

@@ -57,7 +57,6 @@
 #define PHY_SPEED_100FULL  (6)
 #define PHY_DUPLEX         (4)
 
-
 uint32_t eth_phy_read(uint32_t phy_addr, uint32_t reg);
 void eth_phy_write(uint32_t phy_addr, uint32_t reg, uint32_t val);