uacce: fix the big_memeory reserve

driver inclusion
category:bugfix
bugzilla:NA
CVE:NA

when u reserved a big memory(eg: 4G), (unsigned int)nr_pages is too big,
so "nr_pages << PAGE_SHIFT" overflows, the kernel may alloc the memory
to u, but the vm is wrong.

Feature or Bugfix: Bugfix

Signed-off-by: yumeng <yumeng18@huawei.com>
Reviewed-by: xuzaibo <xuzaibo@huawei.com>
Reviewed-by: Zhou Wang <wangzhou1@hisilicon.com>
Reviewed-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>