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/PMC440_defconfig b/configs/PMC440_defconfig
index 00edbee..6ef6058 100644
--- a/configs/PMC440_defconfig
+++ b/configs/PMC440_defconfig
@@ -21,6 +21,7 @@
 CONFIG_CMD_BSP=y
 CONFIG_CMD_DATE=y
 CONFIG_CMD_FAT=y
+# CONFIG_CMD_IRQ is not set
 CONFIG_MAC_PARTITION=y
 CONFIG_ISO_PARTITION=y
 # CONFIG_MMC is not set