crypto: caam - strip input without changing crypto request

For rsa and pkcs1pad, CAAM expects an input of modulus size.
For this we strip the leading zeros in case the size is more than modulus.
This commit avoids modifying the crypto request while stripping zeros from
input, to comply with the crypto API requirement. This is done by adding
a fixup input pointer and length.

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Reviewed-by: Horia Geanta <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>