staging: binder: add __user annotation in binder.c

Add __user to binder_version to correct sparse warning.
Reduce line size to fit to coding style.

Change-Id: I8694fb5a082721c69d1596b2853c5d4899f6536b
Signed-off-by: Mathieu Maret <mathieu.maret@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>