d_shortname of struct dentry only reserves D_NAME_INLINE_LEN characters
and contains garbage for longer names. Use d_name instead, which always
references the valid name.
Link: https://lore.kernel.org/all/20250525213709.878287-2-illia@xxxxxxxxx/
Fixes: 79300ac805b672a84b64 ("scripts/gdb: fix dentry_name() lookup")
Signed-off-by: Illia Ostapyshyn <illia@xxxxxxxxx>