runqemu: allow multiple unfs instances to run simultaneously

A miscalculation in the way the port numbers of mountd and nfsd
are created was causing conflicts when starting multiple instances
of qemu using userspace nfs.

Thanks to Rudolf Streif for proposing this fix!

Fixes [YOCTO #1969]

(From OE-Core rev: 94eef772c283170d19ba92c8de0054cd093fc487)

Signed-off-by: Scott Garman <scott.a.garman@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu-export-rootfs

@@ -82,9 +82,9 @@ NFS_MOUNTPROG=$[ 21111 + $NFS_INSTANCE ]
 # rpc.nfsd RPC port
 NFS_NFSPROG=$[ 11111 + $NFS_INSTANCE ]
 # NFS port number
-NFS_PORT=$[ 3049 + $NFS_INSTANCE ]
+NFS_PORT=$[ 3049 + 2 * $NFS_INSTANCE ]
 # mountd port number
-MOUNT_PORT=$[ 3048 + $NFS_INSTANCE ]
+MOUNT_PORT=$[ 3048 + 2 * $NFS_INSTANCE ]
 
 ## For debugging you would additionally add
 ## --debug all

scripts/runqemu-internal

@@ -277,8 +277,8 @@ if [ "$FSTYPE" = "nfs" ]; then
     NFS_DIR=`echo $ROOTFS | sed 's/^[^:]*:\(.*\)/\1/'`
     MOUNTD_RPCPORT=$[ 21111 + $NFS_INSTANCE ]
     NFSD_RPCPORT=$[ 11111 + $NFS_INSTANCE ]
-    NFSD_PORT=$[ 3049 + $NFS_INSTANCE ]
-    MOUNTD_PORT=$[ 3048 + $NFS_INSTANCE ]
+    NFSD_PORT=$[ 3049 + 2 * $NFS_INSTANCE ]
+    MOUNTD_PORT=$[ 3048 + 2 * $NFS_INSTANCE ]
     UNFS_OPTS="nfsvers=2,mountprog=$MOUNTD_RPCPORT,nfsprog=$NFSD_RPCPORT,udp,port=$NFSD_PORT,mountport=$MOUNTD_PORT"
 
     PSEUDO_LOCALSTATEDIR=~/.runqemu-sdk/pseudo