PCI/MSI: Remove obsolete sanity checks for multiple interrupt sets

Multiple interrupt sets for affinity spreading are now handled in the core
code and the number of sets and their size is recalculated via a driver
supplied callback.

That avoids the requirement to invoke pci_alloc_irq_vectors_affinity() with
the arguments minvecs and maxvecs set to the same value and the callsite
handling the ENOSPC situation.

Remove the now obsolete sanity checks and the related comments.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bjorn Helgaas <helgaas@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: linux-nvme@lists.infradead.org
Cc: linux-pci@vger.kernel.org
Cc: Keith Busch <keith.busch@intel.com>
Cc: Sumit Saxena <sumit.saxena@broadcom.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Shivasharan Srikanteshwara <shivasharan.srikanteshwara@broadcom.com>
Link: https://lkml.kernel.org/r/20190216172228.778630549@linutronix.de