image: Move hash checking into its own function

The existing function is long and most of the code is indented a long
way. Before adding yet more code, split this out into its own function.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de> (v1)
diff --git a/include/image.h b/include/image.h
index 59e8064..507ce42 100644
--- a/include/image.h
+++ b/include/image.h
@@ -43,12 +43,17 @@
 #define CONFIG_OF_LIBFDT	1
 #define CONFIG_FIT_VERBOSE	1 /* enable fit_format_{error,warning}() */
 
+#define IMAGE_ENABLE_IGNORE	0
+
 #else
 
 #include <lmb.h>
 #include <asm/u-boot.h>
 #include <command.h>
 
+/* Take notice of the 'ignore' property for hashes */
+#define IMAGE_ENABLE_IGNORE	1
+
 #endif /* USE_HOSTCC */
 
 #if defined(CONFIG_FIT)
@@ -607,9 +612,6 @@
 int fit_image_hash_get_algo(const void *fit, int noffset, char **algo);
 int fit_image_hash_get_value(const void *fit, int noffset, uint8_t **value,
 				int *value_len);
-#ifndef USE_HOSTCC
-int fit_image_hash_get_ignore(const void *fit, int noffset, int *ignore);
-#endif
 
 int fit_set_timestamp(void *fit, int noffset, time_t timestamp);
 int fit_set_hashes(void *fit);