Add sdeventplus dep to buttons recipe

The button-handler now uses an sdeventplus event loop.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I0e82bf2568863a4e1eff8d1c3d7e00486e694fd6
diff --git a/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb b/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb
index fff4f8e..1bcb3b7 100644
--- a/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb
+++ b/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb
@@ -5,6 +5,7 @@
 DEPENDS += " \
     systemd \
     sdbusplus \
+    sdeventplus \
     phosphor-dbus-interfaces \
     phosphor-logging \
     "