runqemu: independent network and rootfs setup

Presently, runqemu sets up rootfs as part of network setup.
In case there is no network desired we will end up without rootfs
as well.
This patch sets up network and rootfs independently.
It is also possible to bypass setup of rootfs if QB_ROOTFS is set to "none".

(From OE-Core rev: 006ab8c6bcfe9d065c215cab15289357cefc9259)

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu

@@ -935,6 +935,9 @@ class BaseConfig(object):
         else:
             self.setup_tap()
 
+    def setup_rootfs(self):
+        if self.get('QB_ROOTFS') == 'none':
+            return
         rootfs_format = self.fstype if self.fstype in ('vmdk', 'qcow2', 'vdi') else 'raw'
 
         qb_rootfs_opt = self.get('QB_ROOTFS_OPT')
@@ -1167,6 +1170,7 @@ def main():
     config.print_config()
     try:
         config.setup_network()
+        config.setup_rootfs()
         config.setup_final()
         config.start_qemu()
     finally: