USB: ci13xxx_udc:  Add support for UI interrupts counting

Add counting of UI or USB transfers completion interrupts
so that it can be used to determine USB transfers or
BUS usage. This is a simple approach which gives
reasonable accuracy to avoid counting actual bytes
that got transferred over USB.

Change-Id: I1ee3c6997e40ee5db1da26af1e68fced06ea2de4
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>