usb: Update the RequestedActivation property

Subscribe to the add software interface, when an update is detected,
call back the updateActivation method and verify whether it needs
to be updated. If necessary:
1. Set ApplyTime to OnReset to prevent the bmc from restarting
   immediately after the update.
2. Change the RequestedActivation attribute value and start to update
   the image bmc.

Tested: Manually start the phopshor-usb-manager daemon, and saw that
the bmc upgrade file(*.tar) has been copied to /tmp/images and
the update has been triggered, and bmc has not been restarted
immediately.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: Ic650e34f8ec61d3c826332d28275db90f9ef348e
diff --git a/subprojects/sdeventplus.wrap b/subprojects/sdeventplus.wrap
new file mode 100644
index 0000000..085bb5e
--- /dev/null
+++ b/subprojects/sdeventplus.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://github.com/openbmc/sdeventplus.git
+revision = HEAD