HID: thrustmaster: fix memory leak in thrustmaster_interrupts()

In thrustmaster_interrupts(), the allocated send_buf is not
freed if the usb_check_int_endpoints() check fails, leading
to a memory leak.

Fix this by ensuring send_buf is freed before returning in
the error path.

Fixes: 50420d7c ("HID: hid-thrustmaster: Fix warning in thrustmaster_probe by adding endpoint check")
Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>