cryptsetup: disable on broken NIOS 2 toolchains

This package triggers the infamous _gp issue with the external NIOS 2
toolchains, so let's disable it.

Fixes:

  http://autobuild.buildroot.org/results/ff4/ff456344eb5bc8af619c1f5d88be0cb758dd5075/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>