crda: needs dynamic library support

Fixes:
http://autobuild.buildroot.net/results/d75/d752a8d53ad9219b60113075c91c4dcc3e4027c1/



Even if the build system were fixed to deal with that it's only really
useful for systemd/udev scenarios with require dynamic libs as well.
For static scenarios people should look at using
CONFIG_CFG80211_INTERNAL_REGDB in the kernel.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>