crypto: caam - Change kmalloc to kzalloc to avoid residual data

Since fields must be ORed in to operate correctly using any order of
operations, changed allocations of the combination of extended
descriptor structs + hardware scatterlists to use kzalloc() instead
of kmalloc(), so as to ensure that residue data would not be ORed in
with the correct data.

Signed-off-by: Steve Cornelius <steve.cornelius@freescale.com>
Signed-off-by: Victoria Milhoan <vicki.milhoan@freescale.com>
Tested-by: Horia Geantă <horia.geanta@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>