Convert CONFIG_CMD_IRQ to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_IRQ

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index be6b314..1dc8ba2 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1192,6 +1192,14 @@
 	  available tests and running either all the tests, or specific tests
 	  identified by name.
 
+config CMD_IRQ
+	bool "irq - Show information about interrupts"
+	depends on !ARM && !MIPS && !SH && !MPC512X
+	help
+	  This enables two commands:
+
+	     interrupts - enable or disable interrupts
+	     irqinfo - print device-specific interrupt information
 endmenu
 
 config CMD_UBI