package/gcc: remove gcc 5.5 or1k fork

package/gcc: remove gcc 5.5 or1k fork

Remove the old gcc 5.5 fork for or1k architecture
that start to fail to build with recent version
of Binutils >= 2.32 with the following error:

host-gcc-final-or1k-musl-5.4.0-20170218/build/./gcc/crtbeginS.o: addend should be zero for plt relocations
host/or1k-buildroot-linux-uclibc/bin/ld: final link failed: bad value

https://gitlab.com/kubu93/buildroot/-/jobs/391938988

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>