Unmap a page obtained by dma_buf_kmap.
void dma_buf_kunmap(struct dma_buf * dmabuf, unsigned long page_num, void * vaddr);
dmabuf
[in] buffer to unmap page from.
page_num
[in] page in PAGE_SIZE units to unmap.
vaddr
[in] kernel space pointer obtained from dma_buf_kmap.
This call must always succeed.