zipl: Extend disk_get_info() to recognize NVMe disks

Until now, NVMe disks were handled by zipl as SCSI disks. To support
NVMe stand-alone dump, it became necessary to further differentiate between
both types of disks.

There are two cases that must be handled:
1. A non-device-mapper device is a NVMe disk if it is assigned to the blkext
   device driver.
2. A device-mapper disk is a NVMe disk if the ioctl NVME_IOCTL_ID succeeds.
   This case is necessary to properly recognize NVMe disks which are
   DM devices and, therefore, not directly handled by the blkext device
   driver.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Acked-by: Stefan Haberland <sth@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zipl/include/disk.h

@@ -88,6 +88,7 @@ struct disk_info {
 	char* drv_name;
 	source_t source;
 	definition_t targetbase;
+	int is_nvme;
 };
 
 struct file_range {