scripts/gdb: fix dentry_name() lookup

The "d_iname" member was replaced with "d_shortname.string" in the commit
referenced in the Fixes tag.  This prevented the GDB script "lx-mount"
command to properly function:

(gdb) lx-mounts
      mount          super_block     devname pathname fstype options
0xff11000002d21180 0xff11000002d24800 rootfs / rootfs rw 0 0
0xff11000002e18a80 0xff11000003713000 /dev/root / ext4 rw,relatime 0 0
Python Exception <class 'gdb.error'>: There is no member named d_iname.
Error occurred in Python: There is no member named d_iname.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 58cf9c383c ("dcache: back inline names with a struct-wrapped array of unsigned long")
Signed-off-by: Florian Fainelli <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jan Kiszka <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Kieran Bingham <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

scripts/gdb/linux/vfs.py

@@ -22,7 +22,7 @@ def dentry_name(d):
     if parent == d or parent == 0:
         return ""
     p = dentry_name(d['d_parent']) + "/"
-    return p + d['d_iname'].string()
+    return p + d['d_shortname']['string'].string()
 
 class DentryName(gdb.Function):
     """Return string of the full path of a dentry.