fbcon: remove consw::con_screen_pos()

fbcon: remove consw::con_screen_pos()

fbcon_screen_pos() performs the same as the default implementation. The
only difference in the default implementation is that is considers both
vc->vc_origin and vc->vc_visible_origin. But given fbcon's softscroll
code was already removed in commit 50145474f6ef (fbcon: remove soft
scrollback code), both are always the same.

So remove fbcon_screen_pos() too.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-40-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>