ARM: OMAP3: Fix formatting of features printed

With the printk cleanups merged into v4.9-rc1, we now get the omap
revision printed on multiple lines. Let's fix that and also remove the
extra empty space at the end of the features. And let's update things
to use scnprintf as suggested by Ivaylo Dimitrov
<ivo.g.dimitrov.75@gmail.com>.

Reported-by: Adam Ford <aford173@gmail.com>
Cc: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Reviewed-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>