Add power level to ft891

https://github.com/Hamlib/Hamlib/issues/462

rigs/yaesu/ft891.c

@@ -92,6 +92,7 @@ const struct rig_caps ft891_caps =
     .transceive =         RIG_TRN_OFF,        /* May enable later as the 950 has an Auto Info command */
     .bank_qty =           0,
     .chan_desc_sz =       0,
+    .rfpower_meter_cal =  FT891_RFPOWER_METER_CAL,
     .str_cal =            FT891_STR_CAL,
     .chan_list =          {
         {   1,  99, RIG_MTYPE_MEM,  NEWCAT_MEM_CAP },

rigs/yaesu/ft891.h

@@ -68,6 +68,16 @@
                RIG_OP_UP|RIG_OP_DOWN|RIG_OP_BAND_UP|RIG_OP_BAND_DOWN|\
                RIG_OP_TO_VFO|RIG_OP_FROM_VFO)
 
+// Borrowed from FLRig -- Thanks to Dave W1HKJ
+#define FT891_RFPOWER_METER_CAL \
+    { \
+        2, \
+        { \
+            {0, 0.0f}, \
+            {100, 100.0f}, \
+        } \
+    }
+
 /* TBC */
 #define FT891_STR_CAL { 16, \
 	       { \