x86: Move UCLASS_IRQ into a separate file

Update this uclass to support the needs of the Apollo Lake ITSS. It
supports four operations.

Move the uclass into a separate directory so that sandbox can use it too.
Add a new Kconfig to control it and enable this on x86.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 71643af..f18aa8f 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -203,6 +203,15 @@
 	  Security Monitor can be transitioned on any security failures,
 	  like software violations or hardware security violations.
 
+config IRQ
+	bool "Intel Interrupt controller"
+	depends on X86 || SANDBOX
+	help
+	  This enables support for Intel interrupt controllers, including ITSS.
+	  Some devices have extra features, such as Apollo Lake. The
+	  device has its own uclass since there are several operations
+	  involved.
+
 config JZ4780_EFUSE
 	bool "Ingenic JZ4780 eFUSE support"
 	depends on ARCH_JZ47XX