tp-qemu: single_driver_install: remove scenarios "downgrade" and "uninstall".

1. Remove scenarios "downgrade" and "uninstall".
This case won't upgrade / install driver after
 downgrade / uninstall, which is not acceptable.
Will write new case to cover those scenarios.
2. rename variant "uninstall".
3. remove some unreasonable cfg.
Signed-off-by: NCong Li <coli@redhat.com>

qemu/tests/cfg/single_driver_install.cfg

@@ -2,10 +2,9 @@
     type = single_driver_install
     only Windows
     cdroms += " virtio winutils"
-    backup_image_before_test = yes
-    restore_image_after_test = yes
     kill_after_test = yes
     login_timeout = 360
+    need_uninstall = no
     driver_install_timeout = 600
     tmp_folder = C:\tmp
     guest_alias = "Win7-32:w7\x86,Win7-64:w7\amd64,Win8-32:w8\x86,Win8-64:w8\amd64,Win8.1-32:w8.1\x86,Win8-64.1:w8.1\amd64,Win10-32:w10\x86,Win10-64:w10\amd64,Win2008-32:2k8\x86,Win2008-64:2k8\amd64,Win2012-64:2k12\amd64,Win2012-64r2:2k12R2\amd64"
@@ -54,11 +53,3 @@
             balloon = balloon0
             balloon_dev_devid = balloon0
             balloon_dev_add_bus = yes
-    variants:
-        - virtio_install:
-            uninstall = False
-        - virtio_downgrade:
-            uninstall = False
-            cdrom_virtio = isos/windows/virtio-win-downgrade.iso
-        - virtio_reinstall:
-            uninstall = True

qemu/tests/single_driver_install.py

@@ -129,8 +129,8 @@ def run(test, params, env):
         show_file_extentions(session)
         session = reboot(vm, session)
 
-        uninstall_flag = params.get("uninstall", "False")
-        if uninstall_flag == "True":
+        uninstall_flag = params.get("need_uninstall", "no")
+        if uninstall_flag == "yes":
             operation = "uninstall_driver"
             error_context.context("Uninstall driver", logging.info)
             install_driver(session, operation)