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/test/Kconfig b/test/Kconfig
index 7f3447a..9b283a5 100644
--- a/test/Kconfig
+++ b/test/Kconfig
@@ -8,6 +8,7 @@
 
 config SPL_UNIT_TEST
 	bool "Unit tests in SPL"
+	depends on SPL
 	# We need to be able to unbind devices for tests to work
 	select SPL_DM_DEVICE_REMOVE
 	help