Fix th.c logic error discovered by cppcheck

https://github.com/Hamlib/Hamlib/issues/1351

rigs/kenwood/th.c

@@ -522,7 +522,7 @@ th_get_vfo_char(RIG *rig, vfo_t *vfo, char *vfoch)
         break;
 
     case 6: /*intended for D700 BC 0,0*/
-        if ((buf[0] == 'B') && (buf[1] == 'C') && (buf[2] == ' ') && (buf[4] = ','))
+        if ((buf[0] == 'B') && (buf[1] == 'C') && (buf[2] == ' ') && (buf[4] == ','))
         {
             vfoc = buf[3];
         }

rigs/kenwood/th.h

@@ -25,7 +25,7 @@
 
 #include "rig.h"
 
-#define TH_VER "20200701"
+#define TH_VER "20231001"
 
 extern int th_transaction (RIG *rig, const char *cmdstr, char *data, size_t datasize);
 extern int th_get_vfo_char(RIG *rig, vfo_t *vfo, char *vfoch);