Convert CONFIG_CMD_HASH to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_HASH

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
[trini: Rework slightly, enable on some boards again]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 7243f78..b05e69a 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -996,6 +996,14 @@
 	  generation/use as key for cryptographic operation. Key
 	  modifier should be 16 byte long.
 
+config CMD_HASH
+	bool "Support 'hash' command"
+	help
+	  This provides a way to hash data in memory using various supported
+	  algorithms (such as SHA1, MD5, CRC32). The computed digest can be
+	  saved to memory or to an environment variable. It is also possible
+	  to verify a hash against data in memory.
+
 config CMD_TPM
 	bool "Enable the 'tpm' command"
 	depends on TPM