nvme/pci: Use async_schedule for initial reset work

This patch schedules the initial controller reset in an async_domain
so that it can be synchronized from wait_for_device_probe(). This way
the kernel waits for the initial nvme controller scan to complete for
all devices before proceeding with the boot sequence, which may have
nvme dependencies.

Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Tested-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>