package/aircrack-ng: powerpc arch requires altivec

The powerpc support in this package currently requires an arch with
altivec accelerator support. This is a bug and the the powerpc arch
should have a non-simd option like ARM/x86.

Upstream issue: https://github.com/aircrack-ng/aircrack-ng/issues/1941

Fixes
http://autobuild.buildroot.net/results/87e82a5e8d0b1c1ff10ec3e59d25bcd56b329075



Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>