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/T2080RDB_SECURE_BOOT_defconfig b/configs/T2080RDB_SECURE_BOOT_defconfig
index f7c3788..f829638 100644
--- a/configs/T2080RDB_SECURE_BOOT_defconfig
+++ b/configs/T2080RDB_SECURE_BOOT_defconfig
@@ -19,6 +19,7 @@
 CONFIG_CMD_PING=y
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_FAT=y
+# CONFIG_CMD_IRQ is not set
 CONFIG_DM=y
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_SPI_FLASH=y