image: Use the correct checks for CRC32

Add a host Kconfig for CRC32. With this we can use CONFIG_IS_ENABLED(CRC32)
directly in the host build, so drop the unnecessary indirection.

Add a few more conditions to SPL_CRC32 to avoid build failures as well as
TPL_CRC32. Also update hash.c to make crc32 optional and to actually take
notice of SPL_CRC32.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 8a8a971..17ce2f6 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -419,7 +419,8 @@
 
 config SPL_CRC32
 	bool "Support CRC32"
-	default y if SPL_LEGACY_IMAGE_SUPPORT
+	default y if SPL_LEGACY_IMAGE_SUPPORT || SPL_EFI_PARTITION
+	default y if SPL_ENV_SUPPORT || TPL_BLOBLIST
 	help
 	  Enable this to support CRC32 in uImages or FIT images within SPL.
 	  This is a 32-bit checksum value that can be used to verify images.
@@ -1419,6 +1420,16 @@
 	  BOOT_DEVICE_BOOTROM (or fall-through to the next boot device in the
 	  boot device list, if not implemented for a given board)
 
+config TPL_CRC32
+	bool "Support CRC32 in TPL"
+	default y if TPL_ENV_SUPPORT || TPL_BLOBLIST
+	help
+	  Enable this to support CRC32 in uImages or FIT images within SPL.
+	  This is a 32-bit checksum value that can be used to verify images.
+	  For FIT images, this is the least secure type of checksum, suitable
+	  for detected accidental image corruption. For secure applications you
+	  should consider SHA1 or SHA256.
+
 config TPL_DRIVERS_MISC
 	bool "Support misc drivers in TPL"
 	help