package/nodejs: remove version choice

Remove the choice of nodejs version.  Now automatically pick nodejs 0.10.x
for armv5 architectures only and the latest nodejs for all other
supported architectures.

Note that the removal of BR2_PACKAGE_NODEJS_5_X is not handled in
Config.in.legacy because buildroot has never been released with this
option included.

Signed-off-by: Martin Bark <martin@barkynet.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>