package: drop remaining BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS

package: drop remaining BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS

Commit 5a3f78c91915 (libaio: bump to 0.3.111) removed the definition of
BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS, and most references. Remove a few
remaining references.

Fixes:
http://autobuild.buildroot.net/results/724/7244c23a0fbcf27547b5ea639d88033b5a7d9f39/
http://autobuild.buildroot.net/results/be4/be43983767e94ab5c64c3cb3de467840fd6635d2/
http://autobuild.buildroot.net/results/798/798a15a9a064d476927bb49bf534c427e9119c4e/

Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>