cmd: add efidebug command

Currently, there is no easy way to add or modify UEFI variables.
In particular, bootmgr supports BootOrder/BootXXXX variables, it is
quite hard to define them as u-boot variables because they are represented
in a complicated and encoded format.

The new command, efidebug, helps address these issues and give us
more friendly interfaces:
 * efidebug boot add: add BootXXXX variable
 * efidebug boot rm: remove BootXXXX variable
 * efidebug boot dump: display all BootXXXX variables
 * efidebug boot next: set BootNext variable
 * efidebug boot order: set/display a boot order (BootOrder)

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index af2bfb4..4bcc5c4 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1407,6 +1407,16 @@
 	  displayed on a simple board-specific display. Implement
 	  display_putc() to use it.
 
+config CMD_EFIDEBUG
+	bool "efidebug - display/configure UEFI environment"
+	depends on EFI_LOADER
+	default n
+	help
+	  Enable the 'efidebug' command which provides a subset of UEFI
+	  shell utility with simplified functionality. It will be useful
+	  particularly for managing boot parameters as  well as examining
+	  various EFI status for debugging.
+
 config CMD_LED
 	bool "led"
 	depends on LED