crypto: s5p-sss - Add and fix kerneldoc

Add missing and fix existing kerneldoc to silence W=1 warnings:

  drivers/crypto/s5p-sss.c:333: warning: Function parameter or member 'pclk' not described in 's5p_aes_dev'
  drivers/crypto/s5p-sss.c:373: warning: Function parameter or member 'sgl' not described in 's5p_hash_reqctx'
  drivers/crypto/s5p-sss.c:373: warning: Function parameter or member 'buffer' not described in 's5p_hash_reqctx'
  drivers/crypto/s5p-sss.c:1143: warning: Function parameter or member 'new_len' not described in 's5p_hash_prepare_sgs'
  drivers/crypto/s5p-sss.c:1143: warning: Excess function parameter 'nbytes' description in 's5p_hash_prepare_sgs'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Kamil Konieczny <k.konieczny@samsung.com>
Acked-by: Kamil Konieczny <k.konieczny@samsung.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>