drm/prime: Use unsigned type for number of pages

The number of pages can never be negative, so an unsigned type is
enough. This also matches the type of the n_pages argument of the
sg_alloc_table_from_pages() function.
Signed-off-by: NThierry Reding <treding@nvidia.com>

drivers/gpu/drm/drm_prime.c

@@ -669,7 +669,7 @@ int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
  * the driver is responsible for mapping the pages into the
  * importers address space for use with dma_buf itself.
  */
-struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages)
+struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_pages)
 {
 	struct sg_table *sg = NULL;
 	int ret;

include/drm/drmP.h

@@ -986,7 +986,7 @@ extern void drm_gem_dmabuf_release(struct dma_buf *dma_buf);
 
 extern int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
 					    dma_addr_t *addrs, int max_pages);
-extern struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages);
+extern struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_pages);
 extern void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg);