drm/i915: silence io mapping/unmapping sparse warnings on different address spaces

drivers/gpu/drm/i915/i915_gem_execbuffer.c:432:52: warning: incorrect type in argument 1 (different address spaces)
drivers/gpu/drm/i915/i915_gem_execbuffer.c:432:52:    expected void [noderef] <asn:2>*vaddr
drivers/gpu/drm/i915/i915_gem_execbuffer.c:432:52:    got void *
drivers/gpu/drm/i915/i915_gem_execbuffer.c:477:15: warning: incorrect type in assignment (different address spaces)
drivers/gpu/drm/i915/i915_gem_execbuffer.c:477:15:    expected void *vaddr
drivers/gpu/drm/i915/i915_gem_execbuffer.c:477:15:    got void [noderef] <asn:2>*

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1475574853-4178-2-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -429,7 +429,7 @@ static void *reloc_iomap(struct drm_i915_gem_object *obj,
 	}
 
 	if (cache->vaddr) {
-		io_mapping_unmap_atomic(unmask_page(cache->vaddr));
+		io_mapping_unmap_atomic((void __force __iomem *) unmask_page(cache->vaddr));
 	} else {
 		struct i915_vma *vma;
 		int ret;
@@ -474,7 +474,7 @@ static void *reloc_iomap(struct drm_i915_gem_object *obj,
 		offset += page << PAGE_SHIFT;
 	}
 
-	vaddr = io_mapping_map_atomic_wc(&cache->i915->ggtt.mappable, offset);
+	vaddr = (void __force *) io_mapping_map_atomic_wc(&cache->i915->ggtt.mappable, offset);
 	cache->page = page;
 	cache->vaddr = (unsigned long)vaddr;