lib: rsa: decouple rsa from FIT image verification

Introduce new configuration, CONFIG_RSA_VERIFY which will decouple building
RSA functions from FIT verification and allow for adding a RSA-based
signature verification for other file formats, in particular PE file
for UEFI secure boot.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/image-fit.c b/common/image-fit.c
index f3bb00c..9357e66 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -1269,7 +1269,7 @@
 	int ret;
 
 	/* Verify all required signatures */
-	if (IMAGE_ENABLE_VERIFY &&
+	if (FIT_IMAGE_ENABLE_VERIFY &&
 	    fit_image_verify_required_sigs(fit, image_noffset, data, size,
 					   gd_fdt_blob(), &verify_all)) {
 		err_msg = "Unable to verify required signature";
@@ -1291,7 +1291,7 @@
 						 &err_msg))
 				goto error;
 			puts("+ ");
-		} else if (IMAGE_ENABLE_VERIFY && verify_all &&
+		} else if (FIT_IMAGE_ENABLE_VERIFY && verify_all &&
 				!strncmp(name, FIT_SIG_NODENAME,
 					strlen(FIT_SIG_NODENAME))) {
 			ret = fit_image_check_sig(fit, noffset, data,
@@ -1949,7 +1949,7 @@
 		if (image_type == IH_TYPE_KERNEL)
 			images->fit_uname_cfg = fit_base_uname_config;
 
-		if (IMAGE_ENABLE_VERIFY && images->verify) {
+		if (FIT_IMAGE_ENABLE_VERIFY && images->verify) {
 			puts("   Verifying Hash Integrity ... ");
 			if (fit_config_verify(fit, cfg_noffset)) {
 				puts("Bad Data Hash\n");