usb: dwc3: Remove extra format specifier

Correct number of arguments are not passed to the dev_dbg
call here. This is leading to access of garbage value.
Fix this by removing the extra format specifier in the
string.

Change-Id: Id64a00c1ca44c5ee2014fd806c234f702a7941f6
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>