wiringpi: disable for static build

Static build of the wiringPi package is disabled by the tool author
(see wiringPi/noMoreStatic for details) since the version bump
to 2.46.

Fixes [1]:

  arm-linux-gcc.br_real: error: ../wiringPi/libwiringPi.a: No such file or directory

[1] http://autobuild.buildroot.net/results/a1ca953247475a5f31fe9283ade05c9cba26853b



Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>