usb: gadget: printer: eliminate file global printer_mutex

The mutex is a legacy after semi-automatic Big Kernel Lock removal.
printer_open() does its own locking, so no need to duplicate it.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
1 file changed