[explorer] disks: use echo instead of find as fallback

Fixes #761

cdist/conf/explorer/disks

@@ -21,10 +21,7 @@ case "$os" in
             lsblk -e 1,2,11 -dno name | xargs
         else
             # fallback
-            find /dev \
+            cd /dev && echo [vsh]d?
-                -type b \
-                -regex '/dev/\(hd\|sd\|vd\)[a-z]+' \
-                -printf '%f '
         fi
     ;;
 esac