usb: gadget: printer: delete some dead code

"num" is a u16 so it can't go higher than 65535.  kstrtou16() has a
range check built in so this is already handled.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --cc drivers/usb/gadget/function/f_printer.c
Simple merge