Convert CONFIG_CMD_LZMADEC to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_LZMADEC

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index dc81913..5ee52f6 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -438,6 +438,17 @@
 	help
 	  Display memory information.
 
+endmenu
+
+menu "Compression commands"
+
+config CMD_LZMADEC
+	bool "lzmadec"
+	select LZMA
+	help
+	  Support decompressing an LZMA (Lempel-Ziv-Markov chain algorithm)
+	  image from memory.
+
 config CMD_UNZIP
 	bool "unzip"
 	help