MIPS: BCM47XX: Check all (32) GPIOs when looking for a pin

Broadcom boards support 32 GPIOs and NVRAM may have entires for higher
ones too. Example:
gpio23=wombo_reset

Signed-off-by: Rafa? Mi?ecki <zajec5@gmail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-mips@linux-mips.org
Cc: Rafał Miłecki <zajec5@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/6547/


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