fbdev: tcx.c fix mem_map to correct smem_start offset

403ae52ac047 ("sparc: fix drivers/video/tcx.c warning") changed the
physbase initializing breaking the user-space mmap, e.g. for Xorg
entirely.

Fix fbdev mmap table so the sbus mmap helper work correctly, and
not try to map vastly (physbase) offset memory.

Fixes: 403ae52ac047 ("sparc: fix drivers/video/tcx.c warning")
Cc: <[e-mail]>
Signed-off-by: René Rebe <[e-mail]>
Signed-off-by: Helge Deller <[e-mail]>

drivers/video/fbdev/tcx.c

···
 			j = i;
 			break;
 		}
-		par->mmap_map[i].poff = op->resource[j].start;
+		par->mmap_map[i].poff = op->resource[j].start - info->fix.smem_start;
 	}
 
 	info->fbops = &tcx_ops;