staging/fbtft: Update TODO and mailing lists

Motivated by the ksummit-discuss discussion.

Cc: Shuah Khan <shuahkhan@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>