crypto: caam - remove unneeded edesc zeroization

Extended descriptor allocation has been changed by
commit dde20ae9

 ("crypto: caam - Change kmalloc to kzalloc to avoid residual data")
to provide zeroized memory, meaning we no longer have to sanitize
its members - edesc->src_nents and edesc->dst_dma.

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>