add execution permission to "input" script (DO NOT MERGE)

Although when building system image, "input" script will be given execution
permission, adb sync will push a version without x onto device from build
tree. Refer to frameworks/base/cmds/svc/svc, which has execution bit set.

Change-Id: Ie82df2f0d3150c3df9498399f2c446f07ea89ca5