cmd: Add pause command

This command is being introduced with the goal of allowing user-friendly
"generic use case" U-Boot builds to pause until user input under some
situations.

The main use case would be when a boot failure happens, to pause until
the user has had time to acknowledge the current state.

Tested using:

    make && ./u-boot -v -T -c 'ut lib lib_test_hush_pause'

Signed-off-by: Samuel Dionne-Riel <samuel@dionne-riel.com>
Cc: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 211ebe9..67c7d25 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1971,6 +1971,12 @@
 	  milliseconds. See also the 'bootstage' command which provides more
 	  flexibility for boot timing.
 
+config CMD_PAUSE
+	bool "pause command"
+	help
+	  Delay execution waiting for any user input.
+	  Useful to allow the user to read a failure log.
+
 config CMD_RNG
 	bool "rng command"
 	depends on DM_RNG