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 --git a/arch/mips/loongson/Kconfig b/arch/mips/loongson/Kconfig
index 156de85..5064149 100644
--- a/arch/mips/loongson/Kconfig
+++ b/arch/mips/loongson/Kconfig
@@ -15,7 +15,7 @@
 	select HW_HAS_PCI
 	select I8259
 	select ISA
-	select IRQ_CPU
+	select IRQ_MIPS_CPU
 	select SYS_SUPPORTS_32BIT_KERNEL
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_LITTLE_ENDIAN
@@ -44,7 +44,7 @@
 	select HAVE_CLK
 	select HW_HAS_PCI
 	select I8259
-	select IRQ_CPU
+	select IRQ_MIPS_CPU
 	select ISA
 	select SYS_HAS_CPU_LOONGSON2F
 	select SYS_HAS_EARLY_PRINTK
@@ -73,7 +73,7 @@
 	select ISA
 	select HT_PCI
 	select I8259
-	select IRQ_CPU
+	select IRQ_MIPS_CPU
 	select NR_CPUS_DEFAULT_4
 	select SYS_HAS_CPU_LOONGSON3
 	select SYS_HAS_EARLY_PRINTK