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/xpedite517x_defconfig b/configs/xpedite517x_defconfig
index 848d27e..2788db08 100644
--- a/configs/xpedite517x_defconfig
+++ b/configs/xpedite517x_defconfig
@@ -17,6 +17,7 @@
 CONFIG_CMD_SNTP=y
 CONFIG_CMD_DATE=y
 CONFIG_CMD_JFFS2=y
+CONFIG_CMD_IRQ=y
 CONFIG_DS4510=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y