Follow altera_jtag_uart.  This fixes a crash if there is a mistake in the DTS.
Signed-off-by: NYuriy Kozlov <ykozlov@ptcusa.com>
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>