gpe-su: remove unused versions

gpe-su: remove unused versions
 /oe/org.openembedded.dev $ andrea@mizar
 /oe/org.openembedded.dev/conf $ grep -R gpe-su .
 ./checksums.ini:[http://gpe.linuxtogo.org/download/source/gpe-su-0.11.tar.gz]
 ./checksums.ini:[http://gpe.linuxtogo.org/download/source/gpe-su-0.14.tar.gz]
 ./checksums.ini:[http://gpe.linuxtogo.org/download/source/gpe-su-0.15.tar.gz]
 ./checksums.ini:[http://gpe.linuxtogo.org/download/source/gpe-su-0.18.tar.gz]
 ./checksums.ini:[http://gpe.linuxtogo.org/download/source/gpe-su-0.19.tar.gz]
 ./checksums.ini:[http://gpe.linuxtogo.org/download/source/gpe-su-0.20.tar.gz]
 ./distro/include/preferred-gpe-versions-2.8.inc:PREFERRED_VERSION_gpe-su ?= "0.19"
 ./distro/include/preferred-om-2008-versions.inc:PREFERRED_VERSION_gpe-su ?= "0.19"
 ./distro/include/preferred-gpe-versions-2.6.inc:PREFERRED_VERSION_gpe-su ?= "0.18"
 ./distro/include/preferred-gpe-versions-2.7.inc:PREFERRED_VERSION_gpe-su ?= "0.19"
 ./distro/include/preferred-gpe-versions.inc:#PREFERRED_VERSION_gpe-su ?= "0.18"