kunitconfig: changed namespacing of Kconfigs

ALL KUnit test Kconfigs now have the namespace prefix KUNIT_*; this
updates the kunitconfig to fit that.

Change-Id: I879b5bec4fd6f1b3bbebe7686493978aafbb7ac6
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
diff --git a/kunitconfig b/kunitconfig
index d080842..9235b7d 100644
--- a/kunitconfig
+++ b/kunitconfig
@@ -1,3 +1,3 @@
 CONFIG_KUNIT=y
 CONFIG_KUNIT_TEST=y
-CONFIG_EXAMPLE_TEST=y
+CONFIG_KUNIT_EXAMPLE_TEST=y