image: Rename fit_image_check_hashes() to fit_image_verify()

This is the main entry point to the FIT image verification code. We will
be using it to handle image verification with signatures, so rename the
function.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/common/cmd_source.c b/common/cmd_source.c
index f0d7f52..a440614 100644
--- a/common/cmd_source.c
+++ b/common/cmd_source.c
@@ -127,7 +127,7 @@
 
 		/* verify integrity */
 		if (verify) {
-			if (!fit_image_check_hashes (fit_hdr, noffset)) {
+			if (!fit_image_verify(fit_hdr, noffset)) {
 				puts ("Bad Data Hash\n");
 				return 1;
 			}