EVP: Fix evp_pkey_ctx_store_cached_data() to handle provider backed EVP_PKEY_CTX

EVP: Fix evp_pkey_ctx_store_cached_data() to handle provider backed EVP_PKEY_CTX

It assumed there would always be a non-NULL ctx->pmeth, leading to a
crash when that isn't the case.  Since it needs to check 'keytype'
when that one isn't -1, we also add a corresponding check for the
provider backed EVP_PKEY_CTX case.

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/13973)