drivers: net: sam_gmac: remove run once check in update eth_iface_init()

To allow every interface be initialized properly when there are more than one instance, remove the static variable "init_done" which is used to make the initialize procedure only be done once. Signed-off-by: Tony Han <tony.han@microchip.com>

Author: TonyHan11

drivers/ethernet/eth_sam_gmac.c

@@ -1739,7 +1739,6 @@ static void eth_iface_init(struct net_if *iface)
 const struct device *dev = net_if_get_device(iface);
 struct eth_sam_dev_data *const dev_data = dev->data;
 const struct eth_sam_dev_cfg *const cfg = dev->config;
-static bool init_done;
 uint32_t gmac_ncfgr_val;
 int result;
 int i;
@@ -1750,11 +1749,6 @@ static void eth_iface_init(struct net_if *iface)
 
 ethernet_init(iface);
 
-/* The rest of initialization should only be done once */
-if (init_done) {
-return;
-}
-
 /* Check the status of data caches */
 dcache_is_enabled();
 
@@ -1844,8 +1838,6 @@ static void eth_iface_init(struct net_if *iface)
 } else {
 LOG_ERR("%s PHY device not ready", dev->name);
 }
-
-init_done = true;
 }
 
 static enum ethernet_hw_caps eth_sam_gmac_get_capabilities(const struct device *dev)