Update buildroot to 2015.05 base

Adds petitboot to openpower overlay rather rather than in buildroot branch.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/openpower/package/petitboot/removable-event-poll.rules b/openpower/package/petitboot/removable-event-poll.rules
new file mode 100644
index 0000000..b736aef
--- /dev/null
+++ b/openpower/package/petitboot/removable-event-poll.rules
@@ -0,0 +1,4 @@
+
+# petitboot needs notification for media change events on removable devices,
+# which we only get if we've set the poll_msecs sysfs attribute.
+ACTION!="remove", ATTR{removable}=="1", ATTR{events_poll_msecs}="2000"