Remove the 'tarbin' target -- it isn't used as part of the official
QEMU release process, and it's out of date (various new bios files
were never added to its list of files). It's better not to provide
it at all than to have a broken makefile target we never use or test.

(Creating a tarball by just pulling in binaries that have been installed
directly to the system you're running the build on is a bad idea anyway:
the better way to create a binary tarball would be just to install to
a temporary DESTDIR and then tar up that.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>