xhci - clarify compliance mode debug messages

There are no functional changes in this patch. However, because the
compliance mode timer can be deleted in more than one function, it
seemed expedient to include the function name in the debug strings.

Also limited the use of capitals to the first word in the compliance
mode debug messages, except after a function name where all words
start with lower case, in keeping with the style prevalent elsewhere
in xhci.c.

Signed-off-by: Tony Camuso <tcamuso@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>