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_defconfig b/configs/T2080RDB_defconfig
index 595fbbb..424eda1 100644
--- a/configs/T2080RDB_defconfig
+++ b/configs/T2080RDB_defconfig
@@ -17,6 +17,7 @@
 CONFIG_CMD_PING=y
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_FAT=y
+# CONFIG_CMD_IRQ is not set
 CONFIG_FSL_CAAM=y
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_SPI_FLASH=y