scsi: lpfc: Fix use-after-free in lpfc_unreg_rpi() routine

scsi: lpfc: Fix use-after-free in lpfc_unreg_rpi() routine

An error is detected with the following report when unloading the driver:
  "KASAN: use-after-free in lpfc_unreg_rpi+0x1b1b"

The NLP_REG_LOGIN_SEND nlp_flag is set in lpfc_reg_fab_ctrl_node(), but the
flag is not cleared upon completion of the login.

This allows a second call to lpfc_unreg_rpi() to proceed with nlp_rpi set
to LPFC_RPI_ALLOW_ERROR.  This results in a use after free access when used
as an rpi_ids array index.

Fix by clearing the NLP_REG_LOGIN_SEND nlp_flag in
lpfc_mbx_cmpl_fc_reg_login().

Link: https://lore.kernel.org/r/20211020211417.88754-5-jsmart2021@gmail.com
Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>