Fix potential segfault in cmdstr check in kenwood.c

rigs/kenwood/kenwood.c

@@ -517,7 +517,7 @@ transaction_read:
     if (datasize)
     {
         // we ignore the special ;;;;PS; command
-        if (strcmp(cmdstr, ";;;;PS") != 0 && cmdstr && (buffer[0] != cmdstr[0]
+        if (cmdstr && strcmp(cmdstr, ";;;;PS") != 0 && (buffer[0] != cmdstr[0]
                 || (cmdstr[1] && buffer[1] != cmdstr[1])))
         {
             /*

rigs/kenwood/kenwood.h

@@ -28,7 +28,7 @@
 #include "token.h"
 #include "idx_builtin.h"
 
-#define BACKEND_VER "20230219"
+#define BACKEND_VER "20230221"
 
 #define EOM_KEN ';'
 #define EOM_TH '\r'