drm/legacy: Fix type for drm_local_map.offset

drm_local_map.offset is not only used for resource_size_t but also
dma_addr_t which may be of different sizes.

Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Fixes: 8e4ff9b56957 ("drm: Remove the dma_alloc_coherent wrapper for internal usage")
Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200402215926.30714-1-chris@chris-wilson.co.uk
diff --git a/include/drm/drm_legacy.h b/include/drm/drm_legacy.h
index dcef359..aed382c 100644
--- a/include/drm/drm_legacy.h
+++ b/include/drm/drm_legacy.h
@@ -136,7 +136,7 @@
  * Kernel side of a mapping
 struct drm_local_map {
-	resource_size_t offset;	 /**< Requested physical address (0 for SAREA)*/
+	dma_addr_t offset;	 /**< Requested physical address (0 for SAREA)*/
 	unsigned long size;	 /**< Requested physical size (bytes) */
 	enum drm_map_type type;	 /**< Type of memory to map */
 	enum drm_map_flags flags;	 /**< Flags */