crypto: mxs-dcp - Fix platform_get_irq() error handling

We should test the error case for each platform_get_irq() assignment and
propagate the error accordingly.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>