docs/system/arm: Don't use wildcard '*-bmc' in doc titles

docs/system/arm: Don't use wildcard '*-bmc' in doc titles

We have two Arm board doc files which both use '*-bmc' in their
documentation title. The result is that when you read the
table of contents in system/target-arm.html you don't know
which boards are covered by which file.

Expand out the board names entirely in the document titles.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Message-id: 20241018141332.942844-3-peter.maydell@linaro.org