nvmet: pci-epf: clear completion queue IRQ flag on delete

The function nvmet_pci_epf_delete_cq() unconditionally calls
nvmet_pci_epf_remove_irq_vector() even for completion queues that do not
have interrupts enabled. Furthermore, for completion queues that do
have IRQ enabled, deleting and re-creating the completion queue leaves
the flag NVMET_PCI_EPF_Q_IRQ_ENABLED set, even if the completion queue
is being re-created with IRQ disabled.

Fix these issues by calling nvmet_pci_epf_remove_irq_vector() only if
NVMET_PCI_EPF_Q_IRQ_ENABLED is set and make sure to always clear that
flag.

Fixes: 0faa0fe6 ("nvmet: New NVMe PCI endpoint function target driver")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>