crypto: mxs-dcp - Use the devm_clk_get_optional_enabled() helper

Use devm_clk_get_optional_enabled() instead of hand writing it.
This saves some loC and improves the semantic.

update the error handling path and the remove function accordingly.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>