usb: misc: diag_bridge: Patch debug statements

Modify pr_fmt declaration so as to add only function name to the
debug prints. Add new lines in the original print statements. Add
more debug logs where necessary.

Change-Id: Iedf27473174eeae1c8032c133250a190978d38e5
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>