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/configs/kmcoge4_defconfig b/configs/kmcoge4_defconfig
index 9a15d1e..c923aa6 100644
--- a/configs/kmcoge4_defconfig
+++ b/configs/kmcoge4_defconfig
@@ -25,6 +25,7 @@
 CONFIG_CMD_PING=y
 # CONFIG_CMD_HASH is not set
 CONFIG_CMD_JFFS2=y
+# CONFIG_CMD_IRQ is not set
 CONFIG_CMD_UBI=y
 CONFIG_DOS_PARTITION=y
 # CONFIG_MMC is not set