qconfig: Fix an incorrect format-string with negative value

This is not allowed, so use ljust() instead. This fixes the
'qconfig -i -I help' command.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 1bd43060b3 ("moveconfig: Use f strings where possible")

tools/qconfig.py

@@ -1595,7 +1595,7 @@ def imply(args):
             if flag == 'help' or bad:
                 print("Imply flags: (separate with ',')")
                 for name, info in IMPLY_FLAGS.items():
-                    print(f' {name:-15s}: {info[1]}')
+                    print(f' {name.ljust(15)}: {info[1]}')
                 return 1
             imply_flags |= IMPLY_FLAGS[flag][0]