arm64/ascend: Enable DvPP mmap features for Ascend Platform

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4M24Q


CVE: NA

-------------------------------------------------

The DvPP means Davinci Video Pre-Processor, add new config
ASCEND_FEATURES and DVPP_MMAP to enable the DvPP features
for Ascend platform.

The DvPP could only use a limit range of virtual address, just like the
Ascend310/910 could only use the 4 GB range of virtual address, so add
a new mmap flag which is named MAP_DVPP to use the DvPP processor by
mmap syscall, the new flag is only valid for Ascend platform.

You should alloc the memory for dvpp like this:

addr = mmap(NULL, length, PROT_READ, MAP_ANONYMOUS | MAP_DVPP, -1, 0);

Signed-off-by: Lijun Fang <fanglijun3@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>