MIPS: ath79: Fix argument for the ap136_pc_init function

ap136_pci_init expects a u8 pointer as an argument.

Fixes the following build problem on a randconfig:
arch/mips/ath79/mach-ap136.c:151:2: error:
too many arguments to function 'ap136_pci_init'

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5476/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>