linux-headers: remove deprecated versions 3.{0, 11, 13, 15}

Remove for the upcoming 2015.11 release, they've been deprecated for a
year now.
Also remove some previously forgotten selection removals in legacy.

[Peter: drop 3.0.x kernel patch]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>