Revert kenwood RTTY/RTTYR and fix k3.c's DT mode to match it

https://github.com/Hamlib/Hamlib/issues/576

rigs/kenwood/k3.c

@@ -1116,13 +1116,13 @@ int k3_set_mode(RIG *rig, vfo_t vfo, rmode_t mode, pbwidth_t width)
     case RIG_MODE_RTTY:
         mode = RIG_MODE_RTTY; // in "DT1" Subband RIG_MODE_RTTY = LSB and RIG_MODE_RTTYR = USB
         snprintf(cmd_m, sizeof(cmd_m),
-                 "DT1"); /* FSK D mode - direct FSK on LSB optimized for RTTY, VFO dial is MARK */
+                 "DT2"); /* FSK D mode - direct FSK on LSB optimized for RTTY, VFO dial is MARK */
         break;
 
     case RIG_MODE_RTTYR:
         mode = RIG_MODE_RTTYR; // in "DT2" Subband RIG_MODE_RTTY = LSB and RIG_MODE_RTTYR = USB
         snprintf(cmd_m, sizeof(cmd_m),
-                 "DT2"); /* FSK D mode - direct FSK keying, LSB is "normal", VFO dial is MARK */
+                 "DT1"); /* FSK D mode - direct FSK keying, LSB is "normal", VFO dial is MARK */
         break;
 
     case RIG_MODE_PSK:

rigs/kenwood/kenwood.c

@@ -142,12 +142,10 @@ rmode_t kenwood_mode_table[KENWOOD_MODE_TABLE_MAX] =
     [3] = RIG_MODE_CW,
     [4] = RIG_MODE_FM,
     [5] = RIG_MODE_AM,
-    // Yes -- RTTYR is Mode 6 RTTY is LSB, RTTYR USB
-    // FSK mode is mapped the other way round
-    [6] = RIG_MODE_RTTYR, // FSK Mode
+    [6] = RIG_MODE_RTTY, // FSK Mode
     [7] = RIG_MODE_CWR,
     [8] = RIG_MODE_NONE,  /* TUNE mode */
-    [9] = RIG_MODE_RTTY,  // FSKR Mode
+    [9] = RIG_MODE_RTTYR,  // FSKR Mode
     [10] = RIG_MODE_PSK,
     [11] = RIG_MODE_PSKR,
     [12] = RIG_MODE_PKTLSB,

rigs/kenwood/kenwood.h

@@ -28,7 +28,7 @@
 #include "token.h"
 #include "misc.h"
 
-#define BACKEND_VER "20210326"
+#define BACKEND_VER "20210328"
 
 #define EOM_KEN ';'
 #define EOM_TH '\r'