test: change qemu param -nographic to -display none for -daemonize

qemu does not like -nographic in combination with -daemonize

test/TEST-20-NFS/test.sh

@@ -18,7 +18,7 @@ run_server() {
     $testdir/run-qemu \
         -hda $TESTDIR/server.ext3 \
         -m 256M -smp 2 \
-        -nographic \
+        -display none \
         -net nic,macaddr=52:54:00:12:34:56,model=e1000 \
         -net socket,listen=127.0.0.1:12320 \
         -serial $SERIAL \

test/TEST-30-ISCSI/test.sh

@@ -16,7 +16,8 @@ run_server() {
         -hdb $TESTDIR/root.ext3 \
         -hdc $TESTDIR/iscsidisk2.img \
         -hdd $TESTDIR/iscsidisk3.img \
-        -m 256M  -smp 2 -nographic \
+        -m 256M  -smp 2 \
+        -display none \
         -serial $SERIAL \
         -net nic,macaddr=52:54:00:12:34:56,model=e1000 \
         -net socket,listen=127.0.0.1:12330 \

test/TEST-40-NBD/test.sh

@@ -18,7 +18,8 @@ run_server() {
         -hda $TESTDIR/server.ext2 \
         -hdb $TESTDIR/nbd.ext2 \
         -hdc $TESTDIR/encrypted.ext2 \
-        -m 256M -smp 2 -nographic \
+        -m 256M -smp 2 \
+        -display none \
         -net nic,macaddr=52:54:00:12:34:56,model=e1000 \
         -net socket,listen=127.0.0.1:12340 \
         -serial $SERIAL \

test/TEST-50-MULTINIC/test.sh

@@ -18,7 +18,7 @@ run_server() {
     $testdir/run-qemu \
         -hda $TESTDIR/server.ext3 \
         -m 512M -smp 2 \
-        -nographic \
+        -display none \
         -netdev socket,mcast=230.0.0.1:12320,id=net0 \
         -net nic,macaddr=52:54:01:12:34:56,model=e1000,netdev=net0 \
         -serial $SERIAL \