crypto: hisilicon/qm - add comments and remove redundant array element

1. Remove redundant array element, prevent the size obtained by
ARRAY_SIZE() from qm_log_hw_error is greater than actual size.
2. Add comments in function qm_set_vf_mse() and qm_cq_ctx_cfg()
to make it easier to understand.

Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>