MIPS: ath25: add AR2315 PCI host controller driver

Add PCI host controller driver and DMA address calculation hook.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Linux MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/8246/


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