hash: Use Kconfig to enable hashing in host tools and SPL

At present when building host tools, we force CONFIG_SHAxxx to be enabled
regardless of the board Kconfig setting. This is done in the image.h
header file.

For SPL we currently just assume the algorithm is desired if U-Boot proper
enables it.

Clean this up by adding new Kconfig options to enable hashing on the host,
relying on CONFIG_IS_ENABLED() to deal with the different builds.

Add new SPL Kconfigs for hardware-accelerated hashing, to maintain the
current settings.

This allows us to drop the image.h code and the I_WANT_MD5 hack.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

lib/Kconfig

@@ -438,6 +438,24 @@ config SPL_SHA384
 	  The SHA384 algorithm produces a 384-bit (48-byte) hash value
 	  (digest).
 
+config SPL_SHA_HW_ACCEL
+	bool "Enable hardware acceleration for SHA hash functions"
+	default y if SHA_HW_ACCEL
+	help
+	  This option enables hardware acceleration for the SHA1 and SHA256
+	  hashing algorithms. This affects the 'hash' command and also the
+	  hash_lookup_algo() function.
+
+config SPL_SHA_PROG_HW_ACCEL
+	bool "Enable Progressive hashing support using hardware in SPL"
+	depends on SHA_PROG_HW_ACCEL
+	default y
+	help
+	  This option enables hardware-acceleration for SHA progressive
+	  hashing.
+	  Data can be streamed in a block at a time and the hashing is
+	  performed in hardware.
+
 endif
 
 if SHA_HW_ACCEL