Commit 930914b7d528fc ("powerpc/xive: Add a debugfs file to dump
internal XIVE state") forgot to add a null check.
Add it.
Cc: Cédric Le Goater <clg@xxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Fixes: 930914b7d528fc6b0249bffc00564100bcf6ef75 ("powerpc/xive: Add a debugfs file to dump internal XIVE state")
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxx>