ascend inclusion
category: feature
bugzilla: NA
CVE: NA

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

Add alloc and release memory functions in svm. And the physical address
of the memory is within 4GB.

For example:
    /* alloc */
    fd = open("dev/svm0",);
    mmap(0, ALLOC_SIZE,, MAP_PA32BIT, fd, 0);

    /* free */
    ioctl(fd, SVM_IOCTL_RELEASE_PHYS32,);
    close(fd);
Signed-off-by: NBixuan Cui <cuibixuan@huawei.com>
Reviewed-by: NZefan Li <lizefan@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>