8631 only 16 NVMe controllers usable per system due to 18bit minor number limit
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>

@@ -318,11 +318,11 @@
 
 static int nvme_open(dev_t *, int, int, cred_t *);
 static int nvme_close(dev_t, int, int, cred_t *);
 static int nvme_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);
 
-#define NVME_MINOR_INST_SHIFT   14
+#define NVME_MINOR_INST_SHIFT   9
 #define NVME_MINOR(inst, nsid)  (((inst) << NVME_MINOR_INST_SHIFT) | (nsid))
 #define NVME_MINOR_INST(minor)  ((minor) >> NVME_MINOR_INST_SHIFT)
 #define NVME_MINOR_NSID(minor)  ((minor) & ((1 << NVME_MINOR_INST_SHIFT) - 1))
 #define NVME_MINOR_MAX          (NVME_MINOR(1, 0) - 2)