MIPS: TXx9: tx39xx: Move GPIO setup from .mem_setup() to .arch_init()

MIPS: TXx9: tx39xx: Move GPIO setup from .mem_setup() to .arch_init()

txx9_gpio_init() calls gpiochip_add_data(), which fails with -ENOMEM as
it is called too early in the boot process. This causes all subsequent
GPIO operations to fail silently.

Postpone all GPIO setup to .arch_init() time to fix this.

Suggested-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-mips@linux-mips.org
Cc: linux-gpio@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13967/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>