scsi: lpfc: Revise ndlp kref handling for dev_loss_tmo_callbk and lpfc_drop_node

scsi: lpfc: Revise ndlp kref handling for dev_loss_tmo_callbk and lpfc_drop_node

The ndlp kref count implementation in lpfc_dev_loss_tmo_callbk() removes
the initial node reference when a vport is unloading.  When lpfc_cleanup()
sends a DEVICE_RM event and is in NPR state, the driver calls
lpfc_drop_node().  Subsequently, lpfc_drop_node() also removes an ndlp kref
thinking it is the initial reference.  This unintentionally introduces an
extra kref decrement on the ndlp object.

Fix by using the NLP_DROPPED node flag in lpfc_dev_loss_tmo_callbk() and
lpfc_drop_node() to coordinate the removal of the initial node reference.

In lpfc_dev_loss_tmo_callbk(), remove the SCSI transport reference provided
the node is registered in the dev_loss context because the driver cannot
call the SCSI transport in dev_loss context or afterwards.  And, have
lpfc_drop_node() not remove a reference if another thread is acting or has
already acted on it.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20230712180522.112722-6-justintee8345@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>