irqchip: mips-gic: Move gic_get_c0_*_int() to asm/mips-gic.h

The linux/irqchip/mips-gic.h header is now almost empty. Move the
declarations of gic_get_c0_compare_int(), gic_get_c0_perfcount_int() &
gic_get_c0_fdc_int() to asm/mips-gic.h in order to close in on being
able to delete the former header.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17046/


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