tslib: needs kernel headers 3.12

tslib: needs kernel headers 3.12

Kernel headers 3.12+ are required since tslib version 1.3.

https://github.com/kergoth/tslib/blob/master/README.markdown

Update tslib reverse dependencies.

Fixes:
http://autobuild.buildroot.net/results/28d/28df38e2a042f1b5940bf35c18334ebf8810a348/
http://autobuild.buildroot.net/results/c38/c383cfee3673aa9fba36a86f1e68de63413c2987/
http://autobuild.buildroot.net/results/6dd/6ddb2cd9f4f41ee03dc10a73422ad37070811732/

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>