Shellcheck warns that in
 rm -f */config-devices.mak.d
the glob might expand to something with a '-' in it, which would
then be misinterpreted as an option to rm. Fix this by adding './'.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220825150703.4074125-5-peter.maydell@linaro.org