Unify naming: all network stacks are in src/net_...

src/drivers/tm4c.h

@@ -0,0 +1,14 @@
+#pragma once
+
+struct mg_tcpip_driver_tm4c_data {
+  // MDC clock divider. MDC clock is derived from SYSCLK, must not exceed 2.5MHz
+  //    SYSCLK range   DIVIDER   mdc_cr VALUE
+  //    -------------------------------------
+  //                                -1  <-- tell driver to guess the value
+  //    60-100 MHz    SYSCLK/42      0
+  //    100-150 MHz   SYSCLK/62      1  <-- value for EK-TM4C129* on max speed
+  //    20-35 MHz     SYSCLK/16      2
+  //    35-60 MHz     SYSCLK/26      3
+  //    0x4-0xF Reserved
+  int mdc_cr;  // Valid values: -1, 0, 1, 2, 3
+};