pds_core: check for workqueue allocation failure

pds_core: check for workqueue allocation failure

pdsc_init_pf() does not check whether create_singlethread_workqueue()
succeeded.

Fail probe on failure. The workqueue is set up before the timer and
mutexes, so its failure path must unwind only the earlier setup.

Fixes: c2dbb0904310 ("pds_core: health timer and workqueue")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260629200358.2626129-1-nikhil.rao%40amd.com?part=2
Signed-off-by: Nikhil P. Rao <nikhil.rao@amd.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://patch.msgid.link/20260714212713.1788438-1-nikhil.rao@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>