spl: Ensure all SPL symbols in Kconfig have some SPL dependency

Tighten up symbol dependencies in a number of places.  Ensure that a SPL
specific option has at least a direct dependency on SPL.  In places
where it's clear that we depend on something more specific, use that
dependency instead.  This means in a very small number of places we can
drop redundant dependencies.

Reported-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 1c04a7e..152eb2a 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -28,7 +28,7 @@
 
 config SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
 	bool "Asymmetric public-key crypto algorithm subtype within SPL"
-	depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+	depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE && SPL
 	help
 	  This option provides support for asymmetric public key type handling in the SPL.
 	  If signature generation and/or verification are to be used,
@@ -48,7 +48,7 @@
 
 config SPL_RSA_PUBLIC_KEY_PARSER
 	bool "RSA public key parser within SPL"
-	depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+	depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE && SPL
 	select SPL_ASN1_DECODER
 	select ASN1_COMPILER
 	select SPL_OID_REGISTRY