Tweaked dbg script headers to match the mount info log

The main difference being rendering the weight with a single letter "w"
prefix:

  $ ./scripts/dbglfs.py disk -b4096
  littlefs v0.0 4096x256 0x{1,0}.8b w2.512, rev eb7f2a0d
  ...

This lets us add valuable weight info without too much noise.

Adopting this in the dbg scripts is nice for consistency.

scripts/dbgrbyd.py

@@ -1030,7 +1030,7 @@ def main(disk, blocks=None, *,
         weights[i],
         cksums[i])
 
-    print('rbyd %s, rev %08x, size %d, weight %d, cksum %08x' % (
+    print('rbyd %s w%d, rev %08x, size %d, cksum %08x' % (
         '0x%x.%x' % (block, trunk_)
             if len(blocks) == 1
             else '0x{%x,%s}.%x' % (
@@ -1038,7 +1038,10 @@ def main(disk, blocks=None, *,
                 ','.join('%x' % blocks[(i+1+j) % len(blocks)]
                     for j in range(len(blocks)-1)),
                 trunk_),
-        rev, eoff, weight, cksum))
+        weight,
+        rev,
+        eoff,
+        cksum))
 
     if args.get('log'):
         dbg_log(data, block_size, rev, eoff, weight,