sys/phydat: add counts unit

sys/include/phydat.h

@@ -101,6 +101,7 @@ enum {
     UNIT_CD,        /**< Candela */
     /* logical */
     UNIT_BOOL,      /**< boolean value [0|1] */
+    UNIT_CTS,       /**< counts */
     UNIT_PERCENT,   /**< out of 100 */
     UNIT_PERMILL,   /**< out of 1000 */
     UNIT_PPM,       /**< part per million */

sys/phydat/phydat_str.c

@@ -98,6 +98,7 @@ const char *phydat_unit_to_str(uint8_t unit)
         case UNIT_PPB:      return "ppb";
         case UNIT_CD:       return "cd";
         case UNIT_PERCENT:  return "%";
+        case UNIT_CTS:      return "cts";
         default:            return "";
     }
 }