Fix kenwood RD command to use abs value instead of negative sign

https://github.com/Hamlib/Hamlib/issues/341

rigs/kenwood/kenwood.c

@@ -1711,7 +1711,7 @@ int kenwood_set_rit(RIG *rig, vfo_t vfo, shortfreq_t rit)
     if (priv->has_rit2) // if backend shows it has the Set 2 command
     {
         char cmd[10];
-        snprintf(cmd, sizeof(cmd) - 1, "R%c%05d", rit > 0 ? 'U' : 'D', (int)rit);
+        snprintf(cmd, sizeof(cmd) - 1, "R%c%05d", rit > 0 ? 'U' : 'D', abs((int)rit));
         retval = kenwood_transaction(rig, cmd, NULL, 0);
     }
     else

rigs/kenwood/kenwood.h

@@ -27,7 +27,7 @@
 #include <string.h>
 #include "token.h"
 
-#define BACKEND_VER "20200707"
+#define BACKEND_VER "20200712"
 
 #define EOM_KEN ';'
 #define EOM_TH '\r'