chromium: Fix wrong/missing hash for beta channel

The hash provided in commit 072917ea is
faulty, either because the upstream tarball has changed or because it
was wrong in the first place, no matter what happened we can't really
verify if we don't have the tarball with the old hash.

To double-check I've verified the hash against the one from Gentoo[1],
which has the following SHA256:

b46c26a9e773b2c620acd2f96d69408f14a279aefaedfefed002ecf898a1ecf2

After being converted into base 32 the hash does match with ours.

Note that I haven't tested building all Chromium channels (yet), but we
can fix upcoming issues later because right now it doesn't build anyway
because of the failing hash check.

[1]: https://gitweb.gentoo.org/repo/gentoo.git/tree/www-client/chromium/Manifest?id=2de0f5e4ffeb46a478c589b21d5bbcfd5736e57b



Signed-off-by: aszlig <aszlig@redmoonstudios.org>