On XLR/XLS, the cpu cores communicate with fast on-chip devices
(e.g. network accelerator, security engine etc.) using the Fast
Messaging Network(FMN). The FMN queues and credits needs to be
configured and intialized before it can be used.

The co-processor 2 on XLR/XLS CPU cores has registers for FMN access,
and the XLR/XLS has custom instructions for sending and loading
messages.  The FMN can deliver also per-cpu interrupts when messages
are available at the CPU.

This patch adds FMN initialization, adds interrupt setup and handling,
and also provides support for sending and receiving FMN messages.
Signed-off-by: Ganesan Ramalingam <ganesanr@broadcom.com>
Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: http://patchwork.linux-mips.org/patch/4468Signed-off-by: John Crispin <blogic@openwrt.org>