buildroot

toolchain-external: remove useless shell continuations

When a message with MESSAGE, we can print it as the first command of
the command sequence, and in this case, we don't need to use a shell
continuation.

In one case, the call to MESSAGE is moved a few lines up in the
sequence of commands.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>