can: ems_usb: ems_usb_read_bulk_callback(): fix URB memory leak

In the Linux kernel, the following vulnerability has been resolved:

can: ems_usb: ems_usb_read_bulk_callback(): fix URB memory leak

Fix similar memory leak as in commit 7352e1d5932a ("can: gs_usb:

gs_usb_receive_bulk_callback(): fix URB memory leak").

In ems_usb_open(), the URBs for USB-in transfers are allocated, added to

the dev->rx_submitted anchor and submitted. In the complete callback

ems_usb_read_bulk_callback(), the URBs are processed and resubmitted. In

ems_usb_close() the URBs are freed by calling

usb_kill_anchored_urbs(&dev->rx_submitted).

However, this does not take into account that the USB framework unanchors

the URB before the complete function is called. This means that once an

in-URB has been completed, it is no longer anchored and is ultimately not

released in ems_usb_close().

Fix the memory leak by anchoring the URB in the

ems_usb_read_bulk_callback() to the dev->rx_submitted anchor.