NVMe: Change NVME_IOCTL_GET_RANGE_TYPE to return all the ranges

Factor out most of nvme_identify() into a new nvme_submit_user_admin_command()
function.  Change nvme_get_range_type() to call it and change nvme_ioctl to
realise that it's getting back all 64 ranges.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>