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/Makefile b/common/Makefile
index 896e4af..702f239 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -112,7 +112,8 @@
 obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += image-fdt.o
 obj-$(CONFIG_$(SPL_TPL_)FIT) += image-fit.o
 obj-$(CONFIG_$(SPL_)MULTI_DTB_FIT) += boot_fit.o common_fit.o
-obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += image-sig.o
+obj-$(CONFIG_IMAGE_SIGN_INFO) += image-sig.o
+obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += image-fit-sig.o
 obj-$(CONFIG_$(SPL_TPL_)FIT_CIPHER) += image-cipher.o
 obj-$(CONFIG_IO_TRACE) += iotrace.o
 obj-y += memsize.o