NVMe: Only release requested regions

The NVMe driver only requests the PCIe device's memory regions but releases
all possible regions (including eventual I/O regions). This leads to a stale
warning entry in dmesg about freeing non existent resources.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@fb.com>