docs: aspeed: Update OpenBMC image URL

This is the latest URL for the OpenBMC CI. The old URL still works, but
redirects.

Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Message-id: 20211117065752.330632-3-joel@jms.id.au
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/arm/aspeed.rst

@@ -82,7 +82,7 @@ The Aspeed machines can be started using the ``-kernel`` option to
 load a Linux kernel or from a firmware. Images can be downloaded from
 the OpenBMC jenkins :
 
-   https://jenkins.openbmc.org/job/ci-openbmc/lastSuccessfulBuild/distro=ubuntu,label=docker-builder
+   https://jenkins.openbmc.org/job/ci-openbmc/lastSuccessfulBuild/
 
 or directly from the OpenBMC GitHub release repository :