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 <[e-mail]>
Fixes: 8e4ff9b56957 ("drm: Remove the dma_alloc_coherent wrapper for internal usage")
Tested-by: Nathan Chancellor <[e-mail]> # build
Signed-off-by: Chris Wilson <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

include/drm/drm_legacy.h

···
  * 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 */