staging: ft1000: fix memory leak on error path in ft1000_probe()

ft1000dev->tx_urb and ft1000dev->rx_urb are not deallocated
if something goes wrong in ft1000_probe(). Also there is no
check for success of urb allocation. The patch fixes the both issues.

By the way, there is no sense in GFP_ATOMIC for urb allocation here,
so it is changed to GFP_KERNEL.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>