MIPS: Pistachio: Support CDMM & Fast Debug Channel

Implement the mips_cdmm_phys_base() platform callback to provide a
default Common Device Memory Map (CDMM) physical base address for the
Pistachio SoC. This allows the CDMM in each VPE to be configured and
probed for devices, such as the Fast Debug Channel (FDC).

The physical address chosen is just below the default CPC address, which
appears to also be unallocated.

The FDC IRQ is also usable on Pistachio, and is routed through the GIC,
so implement the get_c0_fdc_int() platform callback using
gic_get_c0_fdc_int(), so the FDC driver doesn't have to fall back to
polling.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: James Hartley <james.hartley@imgtec.com>
Cc: linux-mips@linux-mips.org
Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Patchwork: http://patchwork.linux-mips.org/patch/9749/


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