fbcon: Remove fbcon_has_exited

This is unused code since commit 6104c37094e729f3d4ce65797002112735d49cd1 Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Tue Aug 1 17:32:07 2017 +0200 fbcon: Make fbcon a built-time depency for fbdev when fbcon was made a compile-time static dependency of fbdev. We can't exit fbcon anymore without exiting fbdev first, which only works if all fbdev drivers have unloaded already. Hence this is all dead code. v2: I missed that fbcon_exit is also called from con_deinit stuff, and there fbcon_has_exited prevents double-cleanup. But we can fix that by properly resetting con2fb_map[] to all -1, which is used everywhere else to indicate "no fb_info allocate to this console". With that change the double-cleanup (which resulted in a module refcount underflow, among other things) is prevented. Aside: con2fb_map is a signed char, so don't register more than 128 fb_info or hilarity will ensue. v3: CI showed me that I still didn't fully understand what's going on here. The leaked references in con2fb_map have been used upon rebinding the fb console in fbcon_init. It worked because fbdev unregistering still cleaned out con2fb_map, and reset it to info_idx. If the last fbdev driver unregistered, then it also reset info_idx, and unregistered the fbcon driver. Imo that's all a bit fragile, so let's keep the con2fb_map reset to -1, and in fbcon_init pick info_idx if we're starting fresh. That means unbinding and rebinding will cleanse the mapping, but why are you doing that if you want to retain the mapping, so should be fine. Also, I think info_idx == -1 is impossible in fbcon_init - we unregister the fbcon in that case. So catch&warn about that. v4: Drop unecessary assignment - I forgot to delete the first assignment of info in fbcon_init.

DVDaniel Vetter committed 7 years ago