TC: Handle device_register() errors.

Make the TURBOchannel driver bail out if the call to device_register()
failed.

Signed-off-by: Levente Kurusa <levex@linux.com>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Linux MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/6673/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>