can: gs_usb: fix memory leak in gs_cmd_reset()

commit 5cda3ee5138e91ac369ed9d0b55eab0dab077686 upstream.

This patch adds the missing kfree() in gs_cmd_reset() to free the
memory that is not used anymore after usb_control_msg().

Cc: Maximilian Schneider <max@schneidersoft.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>