drm/vmwgfx: Fix a 64bit regression on svga3

Register accesses are always 4bytes, accidently this was changed to
a void pointer whwqich badly breaks 64bit archs when running on top
of svga3.

Fixes: 2cd80db ("drm/vmwgfx: Add basic support for SVGA3")
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210615182336.995192-3-zackr@vmware.com
(cherry picked from commit 8736016)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Author: zackr

drivers/gpu/drm/vmwgfx/vmwgfx_drv.h

@@ -492,7 +492,7 @@ struct vmw_private {
 	resource_size_t vram_start;
 	resource_size_t vram_size;
 	resource_size_t prim_bb_mem;
-	void __iomem *rmmio;
+	u32 __iomem *rmmio;
 	u32 *fifo_mem;
 	resource_size_t fifo_mem_size;
 	uint32_t fb_max_width;