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/Kconfig b/Kconfig
index 66148ce..e2387b2 100644
--- a/Kconfig
+++ b/Kconfig
@@ -354,6 +354,8 @@
 	depends on DM
 	select HASH
 	select RSA
+	select RSA_VERIFY
+	select IMAGE_SIGN_INFO
 	help
 	  This option enables signature verification of FIT uImages,
 	  using a hash signed and verified using RSA. If
@@ -442,6 +444,8 @@
 	depends on SPL_DM
 	select SPL_FIT
 	select SPL_RSA
+	select SPL_RSA_VERIFY
+	select IMAGE_SIGN_INFO
 
 config SPL_LOAD_FIT
 	bool "Enable SPL loading U-Boot as a FIT (basic fitImage features)"