MIPS: BCM63xx: Initialize gpio_out_low & out_high to current value at boot.

To avoid a glitch during GPIO initialisation read GPIO output register
values left by the firmware.

Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/903/


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