reiserfs: fix uninit-value in comp_keys

The cpu_key was not initialized in reiserfs_delete_solid_item(), which triggered
this issue.

Reported-and-tested-by:  <syzbot+b3b14fb9f8a14c5d0267@syzkaller.appspotmail.com>
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Link: https://lore.kernel.org/r/tencent_9EA7E746DE92DBC66049A62EDF6ED64CA706@qq.com


Signed-off-by: Christian Brauner <brauner@kernel.org>