USB: core: remove dead code in do_proc_bulk()

Since len1 is unsigned int, len1 < 0 always false. Remove it keep code
simple.

Signed-off-by: Rex Nie <rex.nie@jaguarmicro.com>
Rule: add
Link: https://lore.kernel.org/stable/20241108094255.2133-1-rex.nie%40jaguarmicro.com


Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20241112152021.2236-1-rex.nie@jaguarmicro.com


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