chore: remove unused fn & only suggest graphs when turbostat exists

plugins/sensors/turbostat_

@@ -98,14 +98,6 @@ function turbostat_exists {
 	return 0
 }
 
-# Left trim white spaces
-function ltrim {
-    local var="$*"
-    # remove leading whitespace characters
-    var="${var#"${var%%[![:space:]]*}"}"
-    echo "$var"
-}
-
 # Emit config for package watt graph
 function emit_watt_graph {
 	local col label
@@ -198,7 +190,9 @@ case $1 in
         fi
         ;;
     suggest)
-		echo "watt"
+		if turbostat_exists; then
+			echo "watt"
+		fi
         ;;
     *)
 		GRAPH_TYPE=${0##*turbostat_}