rasd: Enable and use events ids

Every event has an internal id calculated, it is used to map the
requested events to the received ones.

Signed-off-by: Jean Pihet <jean.pihet@linaro.org>
Link: http://lkml.kernel.org/r/1412933690-25576-6-git-send-email-jean.pihet@linaro.org
Signed-off-by: Borislav Petkov <bp@suse.de>