usb: core: devices: remove dead code under #ifdef PROC_EXTRA

usb_dump_hub_descriptor() and usb_dump_string() are defined under #ifdef
PROC_EXTRA (while PROC_EXTRA doesn't seem to have ever been #define'd)
since the dawn of the git era -- remove this dead code at last...

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

Link: https://lore.kernel.org/r/ec08915b-faf2-2f0b-dfb1-048dfa2c67f3@omp.ru


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>