MIPS/IRQCHIP: Move irq_chip from arch/mips to drivers/irqchip.

While at it, rename it because in drivers/irqchip no longer every CPU is
a MIPS.

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

diff --cc arch/mips/Kconfig
Simple merge

diff --cc arch/mips/include/asm/irqflags.h
Simple merge

diff --cc arch/mips/include/asm/mach-generic/irq.h
Simple merge

diff --cc arch/mips/include/asm/txx9irq.h
Simple merge

diff --cc arch/mips/kernel/Makefile
Simple merge

diff --cc arch/mips/loongson/Kconfig
Simple merge

diff --cc arch/mips/loongson1/Kconfig
Simple merge

diff --cc arch/mips/sibyte/Kconfig
Simple merge

diff --cc arch/mips/txx9/Kconfig
Simple merge

diff --cc arch/mips/vr41xx/Kconfig
Simple merge

diff --cc drivers/irqchip/Kconfig
Simple merge

diff --cc drivers/irqchip/Makefile
Simple merge

diff --cc drivers/irqchip/irq-mips-cpu.c
Simple merge