Convert CONFIG_CMD_BMODE to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_BMODE

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Make this default y and depend on mx5/6/7]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/imx-common/Kconfig b/arch/arm/imx-common/Kconfig
index 7ee74d5..5eb3ba0 100644
--- a/arch/arm/imx-common/Kconfig
+++ b/arch/arm/imx-common/Kconfig
@@ -32,3 +32,17 @@
 	help
 	  This option enables the support for secure boot (HAB).
 	  See doc/README.mxc_hab for more details.
+
+config CMD_BMODE
+	bool "Support the 'bmode' command"
+	default y
+	depends on ARCH_MX7 || ARCH_MX6 || ARCH_MX5
+	help
+	  This enables the 'bmode' (bootmode) command for forcing
+	  a boot from specific media.
+
+	  This is useful for forcing the ROM's usb downloader to
+	  activate upon a watchdog reset which is nice when iterating
+	  on U-Boot.  Using the reset button or running bmode normal
+	  will set it back to normal.  This command currently
+	  supports i.MX53 and i.MX6.