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>

lib: ecdsa: Implement UCLASS_ECDSA verification on target

Implement the crypto_algo .verify() function for ecdsa256. Because
it backends on UCLASS_ECDSA, this change is focused on parsing the
keys from devicetree and passing this information to the specific
UCLASS driver.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

lib: ecdsa: Implement UCLASS_ECDSA verification on target

Implement the crypto_algo .verify() function for ecdsa256. Because
it backends on UCLASS_ECDSA, this change is focused on parsing the
keys from devicetree and passing this information to the specific
UCLASS driver.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>