This patch allocates snapshot memory for global reg,
port regs, CQ, DQ, IOST, ITCT.

when we fail to allocate memory for one of registers,
we free the momory and set hisi_sas_debugfs_enable
as 0 to stop dfx from running.
Signed-off-by: NLuo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>