Makefile: use $(Q) instead of @ to silence target-finalize commands

As 18f6c261 just did to silence the file lists commands, switch to
using $(Q) instead of a plain @, to silence the commands.

Using $(Q) will allow to debug the commands with V=1.

We keep @ for the calls to MESSAGE, though.

The commands that are not currently silenced are left as-is, and they
can be converted to being silent in a followup patch, if need be,

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>