MIPS: BCM47xx: Fix gpio_direction_output

gpio_direction_output should also set an output value according to the API.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>