bhyve: implement NVMe device support

NVMe devices in bhyve are modeled this way:

 -s $pciaddr,nvme,devpath[,opts]

devpath can be a path to the image or the block device. It also can be
"ram=size_in_MiB", but this is not covered by this series.

There could be only a single device per PCI address.

Optional configuration options (such as max number of queues, concurrent
I/O requests, etc) are also not covered by this series.

Signed-off-by: Roman Bogorodskiy <bogorodskiy@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

tests/bhyvexml2argvdata/bhyvexml2argv-nvme.args

@@ -0,0 +1,9 @@
+bhyve \
+-c 1 \
+-m 214 \
+-u \
+-H \
+-P \
+-s 0:0,hostbridge \
+-s 2:0,nvme,/tmp/freebsd.img \
+bhyve

tests/bhyvexml2argvdata/bhyvexml2argv-nvme.ldargs

@@ -0,0 +1,4 @@
+bhyveload \
+-m 214 \
+-d /tmp/freebsd.img \
+bhyve

tests/bhyvexml2argvdata/bhyvexml2argv-nvme.xml

@@ -0,0 +1,16 @@
+<domain type='bhyve'>
+  <name>bhyve</name>
+  <uuid>df3be7e7-a104-11e3-aeb0-50e5492bd3dc</uuid>
+  <memory>219136</memory>
+  <vcpu>1</vcpu>
+  <os>
+    <type>hvm</type>
+  </os>
+  <devices>
+    <disk type='file'>
+      <driver name='file' type='raw'/>
+      <source file='/tmp/freebsd.img'/>
+      <target dev='nvme0n1' bus='nvme'/>
+    </disk>
+  </devices>
+</domain>