extmod: Revert accidental usocket->socket rename.

The registration of the usocket module was accidentally changed to socket
in moving to MP_REGISTER_MODULE in bb794f05b7

extmod/modlwip.c

@@ -1781,6 +1781,6 @@ const mp_obj_module_t mp_module_lwip = {
 MP_REGISTER_MODULE(MP_QSTR_lwip, mp_module_lwip, MICROPY_PY_LWIP);
 
 // On LWIP-ports, this is the usocket module (replaces extmod/modusocket.c).
-MP_REGISTER_MODULE(MP_QSTR_socket, mp_module_lwip, MICROPY_PY_LWIP);
+MP_REGISTER_MODULE(MP_QSTR_usocket, mp_module_lwip, MICROPY_PY_LWIP);
 
 #endif // MICROPY_PY_LWIP

extmod/modusocket.c

@@ -588,6 +588,6 @@ const mp_obj_module_t mp_module_usocket = {
     .globals = (mp_obj_dict_t *)&mp_module_usocket_globals,
 };
 
-MP_REGISTER_MODULE(MP_QSTR_socket, mp_module_usocket, MICROPY_PY_NETWORK && MICROPY_PY_USOCKET && !MICROPY_PY_LWIP);
+MP_REGISTER_MODULE(MP_QSTR_usocket, mp_module_usocket, MICROPY_PY_NETWORK && MICROPY_PY_USOCKET && !MICROPY_PY_LWIP);
 
 #endif // MICROPY_PY_NETWORK && MICROPY_PY_USOCKET && !MICROPY_PY_LWIP