LU-14552 ptlrpc: NULL pointer dereference in ptlrpc_watchdog_fire

LU-14552 ptlrpc: NULL pointer dereference in ptlrpc_watchdog_fire

thread->t_task isn't initialized by target_recovery_thread()

Change-Id: Ia38d5ccaab6b9332a1fd60ebe5ed2461f7d5db84
HPE-bug-id: LUS-9748
Fixes: 0496cdf20 ("LU-13608 tgt: abort recovery while reading update llog")
Signed-off-by: Andriy Skulysh <c17819@cray.com>
Reviewed-by: Alexander Boyko <c17825@cray.com>
Reviewed-by: Andrew Perepechko <c17827@cray.com>
Reviewed-on: https://review.whamcloud.com/43115
Reviewed-by: Andrew Perepechko <andrew.perepechko@hpe.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>