MIPS: Netlogic: XLP9XX on-chip SATA support

The XLP9XX SoC has an on-chip SATA controller with two ports. Add
ahci-init-xlp2.c to initialize the controller, setup the glue logic
registers, fixup PCI quirks and setup interrupt ack logic.

Signed-off-by: Ganesan Ramalingam <ganesanr@broadcom.com>
Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6913/


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