MIPS: Malta: Make GIC FDC IRQ workaround Malta specific

MIPS: Malta: Make GIC FDC IRQ workaround Malta specific

Wider testing reveals that the Fast Debug Channel (FDC) interrupt is
routed through the GIC just fine on Pistachio SoC, even though it
contains interAptiv cores. Clearly the FDC interrupt routing problems
previously observed on interAptiv and proAptiv cores are specific to the
Malta FPGA bitstreams.

Move the workaround for interAptiv and proAptiv out of
gic_get_c0_fdc_int() in the GIC irqchip driver into Malta's
get_c0_fdc_int() platform callback, to allow the Pistachio SoC to use
the FDC interrupt.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: linux-mips@linux-mips.org
Reviewed-by: Andrew Bresticker <abrestic@chromium.org>
Cc: James Hartley <james.hartley@imgtec.com>
Patchwork: http://patchwork.linux-mips.org/patch/9748/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>