usb: msm72k_udc: Add more debugfs support

Add debugfs support for repriming particular endpoint in
case of prime failure. Also add counters for prime failure
and prime timer expiry for each endpoint which will be helpful
for debugging.

Change-Id: I23fd52a0aabfb1636e483bdb4d339f0ecc57f558
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>