Remove unused member tHID_HOST_DEV_CTB::conn_substate

Bug: 163134718
Test: gd/cert/run
Tag: #refactor

Change-Id: I7fcfc640ef7728ae924e55d3ce1f4fa43b09963a

system/stack/hid/hidh_int.h

@@ -41,7 +41,6 @@ typedef struct per_device_ctb {
                          reconn_initiate;
                                  0x04- sdp_disable; */
   uint8_t state;      /* Device state if in HOST-KNOWN mode */
-  uint8_t conn_substate;
   uint8_t conn_tries; /* Remembers the number of connection attempts while
                          CONNECTING */