package/binutils: default to version 2.36.x

Now that we have added version 2.37, it's time to use the 2.36.x
series as the default version.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[Arnout: also update default in binutils.mk]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>