diag: Release wakeup sources correctly

Diag driver is not releasing the wakeup source objects in some
corner error cases. This patch tries to release the wakeup source
objects in those conditions.

Change-Id: Icbc8f4126c8447afe71fb97c1ea13626fb6991d6
Signed-off-by: Ravi Aravamudhan <aravamud@codeaurora.org>