meta-phosphor: dbus-sensors: disable tests by default

Set the OE variable to add extra meson options properly.
Fixes 57272ae3079bd1882ad952283e649fd51a2b91f5.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I061534a7c86a42999f2db0a1f5888f1b7a0f2573
diff --git a/meta-phosphor/recipes-phosphor/sensors/dbus-sensors_git.bb b/meta-phosphor/recipes-phosphor/sensors/dbus-sensors_git.bb
index 28d9d0e..565fc27 100644
--- a/meta-phosphor/recipes-phosphor/sensors/dbus-sensors_git.bb
+++ b/meta-phosphor/recipes-phosphor/sensors/dbus-sensors_git.bb
@@ -70,4 +70,4 @@
 
 S = "${WORKDIR}/git"
 
-OEMESON_EXTRA:append = "-Dtests=disabled"
+EXTRA_OEMESON:append = " -Dtests=disabled"