Kconfig: introduce md5sum command selection

So far CONFIG_MD5SUM would need to be set by a board's include file.
Since the command is really generic, move it over to Kconfig to allow
it to be defined by either a board's defconfig, menuconfig or some
config snippet merged via mergeconfig.sh.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

cmd/Kconfig

@@ -338,6 +338,20 @@ config CMD_CRC32
 	help
 	  Compute CRC32.
 
+config CMD_MD5SUM
+	bool "md5sum"
+	default n
+	select MD5
+	help
+	  Compute MD5 checksum.
+
+config MD5SUM_VERFIY
+	bool "md5sum -v"
+	default n
+	depends on CMD_MD5SUM
+	help
+	  Add -v option to verify data against an MD5 checksum.
+
 config LOOPW
 	bool "loopw"
 	help

lib/Kconfig

@@ -101,6 +101,10 @@ config SHA_PROG_HW_ACCEL
 	  SHA1/SHA256 progressive hashing.
 	  Data can be streamed in a block at a time and the hashing
 	  is performed in hardware.
+
+config MD5
+	bool
+
 endmenu
 
 menu "Compression Support"