crypto: hisilicon/qm - increase the memory of local variables

Increase the buffer to prevent stack overflow by fuzz test. The maximum
length of the qos configuration buffer is 256 bytes. Currently, the value
of the 'val buffer' is only 32 bytes. The sscanf does not check the dest
memory length. So the 'val buffer' may stack overflow.

Signed-off-by: Kai Ye <yekai13@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>