scsi: lpfc: Fix invalid sleeping context in lpfc_sli4_nvmet_alloc()

scsi: lpfc: Fix invalid sleeping context in lpfc_sli4_nvmet_alloc()

The following calltrace was seen:

BUG: sleeping function called from invalid context at mm/slab.h:494
...
Call Trace:
 dump_stack+0x9a/0xf0
 ___might_sleep.cold.63+0x13d/0x178
 slab_pre_alloc_hook+0x6a/0x90
 kmem_cache_alloc_trace+0x3a/0x2d0
 lpfc_sli4_nvmet_alloc+0x4c/0x280 [lpfc]
 lpfc_post_rq_buffer+0x2e7/0xa60 [lpfc]
 lpfc_sli4_hba_setup+0x6b4c/0xa4b0 [lpfc]
 lpfc_pci_probe_one_s4.isra.15+0x14f8/0x2280 [lpfc]
 lpfc_pci_probe_one+0x260/0x2880 [lpfc]
 local_pci_probe+0xd4/0x180
 work_for_cpu_fn+0x51/0xa0
 process_one_work+0x8f0/0x17b0
 worker_thread+0x536/0xb50
 kthread+0x30c/0x3d0
 ret_from_fork+0x3a/0x50

A prior patch introduced a spin_lock_irqsave(hbalock) in the
lpfc_post_rq_buffer() routine. Call trace is seen as the hbalock is held
with interrupts disabled during a GFP_KERNEL allocation in
lpfc_sli4_nvmet_alloc().

Fix by reordering locking so that hbalock not held when calling
sli4_nvmet_alloc() (aka rqb_buf_list()).

Link: https://lore.kernel.org/r/20201020202719.54726-2-james.smart@broadcom.com
Fixes: 411de511c694 ("scsi: lpfc: Fix RQ empty firmware trap")
Cc: <stable@vger.kernel.org> # v4.17+
Co-developed-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>